From d0c42d3da30219ff154023745137411dd6f0c58e Mon Sep 17 00:00:00 2001
From: xoviat <xoviat@users.noreply.github.com>
Date: Fri, 26 Jan 2018 10:57:42 -0600
Subject: [PATCH 01/18] Ignore .vscode

---
 .gitignore | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.gitignore b/.gitignore
index 1d842203ba8..6894e3376df 100644
--- a/.gitignore
+++ b/.gitignore
@@ -36,3 +36,4 @@ coverage.xml
 
 # Scratch Pad for experiments
 .scratch/
+.vscode
\ No newline at end of file

From 6a99774dd78317b13e0e9a64331c633e2d47eff3 Mon Sep 17 00:00:00 2001
From: xoviat <xoviat@users.noreply.github.com>
Date: Fri, 26 Jan 2018 10:58:28 -0600
Subject: [PATCH 02/18] Add cleanup method to build_env

---
 src/pip/_internal/build_env.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/pip/_internal/build_env.py b/src/pip/_internal/build_env.py
index 52a53392c5e..469a4f10c36 100644
--- a/src/pip/_internal/build_env.py
+++ b/src/pip/_internal/build_env.py
@@ -62,3 +62,6 @@ def __exit__(self, exc_type, exc_val, exc_tb):
             os.environ.pop('PYTHONPATH', None)
         else:
             os.environ['PYTHONPATH'] = self.save_pythonpath
+
+    def cleanup(self):
+        self._temp_dir.cleanup()

From 615de6a5718aa618b94f04f8b4b0f61c398bb5e9 Mon Sep 17 00:00:00 2001
From: xoviat <xoviat@users.noreply.github.com>
Date: Fri, 26 Jan 2018 11:01:18 -0600
Subject: [PATCH 03/18] Pass through finder to prepare operation

---
 src/pip/_internal/operations/prepare.py | 14 +++++++-------
 src/pip/_internal/resolve.py            |  2 +-
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/pip/_internal/operations/prepare.py b/src/pip/_internal/operations/prepare.py
index e1d8a2baa81..394e84eb6ef 100644
--- a/src/pip/_internal/operations/prepare.py
+++ b/src/pip/_internal/operations/prepare.py
@@ -64,7 +64,7 @@ def dist(self, finder):
         """Return a setuptools Dist object."""
         raise NotImplementedError(self.dist)
 
-    def prep_for_dist(self):
+    def prep_for_dist(self, finder):
         """Ensure that we can get a Dist for this requirement."""
         raise NotImplementedError(self.dist)
 
@@ -75,7 +75,7 @@ def dist(self, finder):
         return list(pkg_resources.find_distributions(
             self.req.source_dir))[0]
 
-    def prep_for_dist(self):
+    def prep_for_dist(self, finder):
         # FIXME:https://github.com/pypa/pip/issues/1112
         pass
 
@@ -91,7 +91,7 @@ def dist(self, finder):
             )
         return dist
 
-    def prep_for_dist(self):
+    def prep_for_dist(self, finder):
         self.req.run_egg_info()
         self.req.assert_source_matches_version()
 
@@ -101,7 +101,7 @@ class Installed(DistAbstraction):
     def dist(self, finder):
         return self.req.satisfied_by
 
-    def prep_for_dist(self):
+    def prep_for_dist(self, finder):
         pass
 
 
@@ -259,14 +259,14 @@ def prepare_linked_requirement(self, req, session, finder,
                     (req, exc, req.link)
                 )
             abstract_dist = make_abstract_dist(req)
-            abstract_dist.prep_for_dist()
+            abstract_dist.prep_for_dist(finder)
             if self._download_should_save:
                 # Make a .zip of the source_dir we already created.
                 if req.link.scheme in vcs.all_schemes:
                     req.archive(self.download_dir)
         return abstract_dist
 
-    def prepare_editable_requirement(self, req, require_hashes):
+    def prepare_editable_requirement(self, req, require_hashes, finder):
         """Prepare an editable requirement
         """
         assert req.editable, "cannot prepare a non-editable req as editable"
@@ -284,7 +284,7 @@ def prepare_editable_requirement(self, req, require_hashes):
             req.update_editable(not self._download_should_save)
 
             abstract_dist = make_abstract_dist(req)
-            abstract_dist.prep_for_dist()
+            abstract_dist.prep_for_dist(finder)
 
             if self._download_should_save:
                 req.archive(self.download_dir)
diff --git a/src/pip/_internal/resolve.py b/src/pip/_internal/resolve.py
index 247c561c549..5fbf5b9b6ff 100644
--- a/src/pip/_internal/resolve.py
+++ b/src/pip/_internal/resolve.py
@@ -187,7 +187,7 @@ def _get_abstract_dist_for(self, req):
 
         if req.editable:
             return self.preparer.prepare_editable_requirement(
-                req, self.require_hashes
+                req, self.require_hashes, self.finder
             )
 
         # satisfied_by is only evaluated by calling _check_skip_installed,

From 08bec25c56768d10c5ca5b7cf30fa19b66293391 Mon Sep 17 00:00:00 2001
From: xoviat <xoviat@users.noreply.github.com>
Date: Fri, 26 Jan 2018 11:02:41 -0600
Subject: [PATCH 04/18] More eagerly cleanup the requirement

---
 src/pip/_internal/resolve.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/pip/_internal/resolve.py b/src/pip/_internal/resolve.py
index 5fbf5b9b6ff..850af7a6f10 100644
--- a/src/pip/_internal/resolve.py
+++ b/src/pip/_internal/resolve.py
@@ -246,11 +246,12 @@ def _resolve_one(self, requirement_set, req_to_install):
             return []
 
         req_to_install.prepared = True
-        abstract_dist = self._get_abstract_dist_for(req_to_install)
 
         # register tmp src for cleanup in case something goes wrong
         requirement_set.reqs_to_cleanup.append(req_to_install)
 
+        abstract_dist = self._get_abstract_dist_for(req_to_install)
+
         # Parse and return dependencies
         dist = abstract_dist.dist(self.finder)
         try:

From 958a9369f5fbb5be2723b0b53d5a0e17855c782c Mon Sep 17 00:00:00 2001
From: xoviat <xoviat@users.noreply.github.com>
Date: Fri, 26 Jan 2018 11:06:00 -0600
Subject: [PATCH 05/18] Make BuildEnvironment a proprety of Requirement

---
 src/pip/_internal/req/req_install.py | 3 +++
 src/pip/_internal/wheel.py           | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/pip/_internal/req/req_install.py b/src/pip/_internal/req/req_install.py
index d25f17c958b..ed7e20b5476 100644
--- a/src/pip/_internal/req/req_install.py
+++ b/src/pip/_internal/req/req_install.py
@@ -22,6 +22,7 @@
 from pip._vendor.pkg_resources import RequirementParseError, parse_requirements
 
 from pip._internal import wheel
+from pip._internal.build_env import BuildEnvironment
 from pip._internal.compat import native_str
 from pip._internal.download import (
     is_archive_file, is_url, path_to_url, url_to_path,
@@ -128,6 +129,7 @@ def __init__(self, req, comes_from, source_dir=None, editable=False,
         self.prepared = False
 
         self.isolated = isolated
+        self.build_environment = BuildEnvironment(no_clean=True)
 
     @classmethod
     def from_editable(cls, editable_req, comes_from=None, isolated=False,
@@ -880,6 +882,7 @@ def remove_temporary_source(self):
             rmtree(self.source_dir)
         self.source_dir = None
         self._temp_build_dir.cleanup()
+        self.build_environment.cleanup()
 
     def install_editable(self, install_options,
                          global_options=(), prefix=None):
diff --git a/src/pip/_internal/wheel.py b/src/pip/_internal/wheel.py
index 03c1b22b99f..558270906b3 100644
--- a/src/pip/_internal/wheel.py
+++ b/src/pip/_internal/wheel.py
@@ -646,8 +646,8 @@ def _build_one(self, req, output_dir, python_tag=None):
                 "it cannot build a wheel without setuptools. You may need to "
                 "upgrade to a newer version of pip.")
         # Install build deps into temporary directory (PEP 518)
-        with BuildEnvironment(self.no_clean) as prefix:
             self._install_build_reqs(build_reqs, prefix)
+        with req.build_environment as prefix:
             return self._build_one_inside_env(req, output_dir,
                                               python_tag=python_tag,
                                               isolate=True)

From 27cb7f36cc9185ee1aa22a7b2c7e1e88768fc1fe Mon Sep 17 00:00:00 2001
From: xoviat <xoviat@users.noreply.github.com>
Date: Fri, 26 Jan 2018 12:11:00 -0600
Subject: [PATCH 06/18] Install build requirements in the prepare operation

---
 src/pip/_internal/build_env.py          | 11 +++++++
 src/pip/_internal/operations/prepare.py | 44 +++++++++++++++++++++++--
 src/pip/_internal/wheel.py              | 24 --------------
 3 files changed, 52 insertions(+), 27 deletions(-)

diff --git a/src/pip/_internal/build_env.py b/src/pip/_internal/build_env.py
index 469a4f10c36..97ec00aa6fb 100644
--- a/src/pip/_internal/build_env.py
+++ b/src/pip/_internal/build_env.py
@@ -65,3 +65,14 @@ def __exit__(self, exc_type, exc_val, exc_tb):
 
     def cleanup(self):
         self._temp_dir.cleanup()
+
+
+class FakeBuildEnvironment(BuildEnvironment):
+    def __enter__(self):
+        pass
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        pass
+        
+    def cleanup(self):
+        pass
diff --git a/src/pip/_internal/operations/prepare.py b/src/pip/_internal/operations/prepare.py
index 394e84eb6ef..837c8f7a7d8 100644
--- a/src/pip/_internal/operations/prepare.py
+++ b/src/pip/_internal/operations/prepare.py
@@ -3,6 +3,10 @@
 
 import logging
 import os
+import sys
+import itertools
+
+from copy import copy
 
 from pip._vendor import pkg_resources, requests
 
@@ -16,8 +20,12 @@
 )
 from pip._internal.utils.hashes import MissingHashes
 from pip._internal.utils.logging import indent_log
-from pip._internal.utils.misc import display_path, normalize_path
+from pip._internal.utils.misc import display_path, normalize_path, call_subprocess
+from pip._internal.utils.ui import open_spinner
 from pip._internal.vcs import vcs
+from pip._internal.req.req_install import InstallRequirement
+from pip._internal.index import FormatControl
+from pip._internal.build_env import FakeBuildEnvironment
 
 logger = logging.getLogger(__name__)
 
@@ -38,6 +46,19 @@ def make_abstract_dist(req):
         return IsSDist(req)
 
 
+def _install_build_reqs(finder, prefix, build_requirements):
+    finder = copy(finder)
+    finder.format_control = FormatControl(set(), set([":all:"]))
+    urls = [finder.find_requirement(InstallRequirement.from_line(r),
+                                    upgrade=False).url
+            for r in build_requirements]
+    args = [sys.executable, '-m', 'pip', 'install', '--ignore-installed',
+        '--prefix', prefix] + list(urls)
+
+    with open_spinner("Installing build dependencies") as spinner:
+        call_subprocess(args, show_stdout=False, spinner=spinner)
+
+
 class DistAbstraction(object):
     """Abstracts out the wheel vs non-wheel Resolver.resolve() logic.
 
@@ -92,8 +113,25 @@ def dist(self, finder):
         return dist
 
     def prep_for_dist(self, finder):
-        self.req.run_egg_info()
-        self.req.assert_source_matches_version()
+        build_requirements, isolate = self.req.get_pep_518_info()
+
+        if 'setuptools' not in build_requirements:
+            logger.warning(
+                "This version of pip does not implement PEP 516, so "
+                "it cannot build a wheel without setuptools. You may need to "
+                "upgrade to a newer version of pip.")
+
+        if not isolate:
+            self.req.build_environment = FakeBuildEnvironment(no_clean=False)
+
+        with self.req.build_environment as prefix:
+            # Ignore the --no-binary option when installing the build system, so
+            # we don't recurse trying to build a self-hosting build system.
+            if isolate:
+                _install_build_reqs(finder, prefix, build_requirements)
+
+            self.req.run_egg_info()
+            self.req.assert_source_matches_version()
 
 
 class Installed(DistAbstraction):
diff --git a/src/pip/_internal/wheel.py b/src/pip/_internal/wheel.py
index 558270906b3..a5ac3b63642 100644
--- a/src/pip/_internal/wheel.py
+++ b/src/pip/_internal/wheel.py
@@ -617,36 +617,12 @@ def __init__(self, finder, preparer, wheel_cache,
         self.global_options = global_options or []
         self.no_clean = no_clean
 
-    def _install_build_reqs(self, reqs, prefix):
-        # Local import to avoid circular import (wheel <-> req_install)
-        from pip._internal.req.req_install import InstallRequirement
-        from pip._internal.index import FormatControl
-        # Ignore the --no-binary option when installing the build system, so
-        # we don't recurse trying to build a self-hosting build system.
-        finder = copy.copy(self.finder)
-        finder.format_control = FormatControl(set(), set([":all:"]))
-        urls = [finder.find_requirement(InstallRequirement.from_line(r),
-                                        upgrade=False).url
-                for r in reqs]
-
-        args = [sys.executable, '-m', 'pip', 'install', '--ignore-installed',
-                '--prefix', prefix] + list(urls)
-        with open_spinner("Installing build dependencies") as spinner:
-            call_subprocess(args, show_stdout=False, spinner=spinner)
-
     def _build_one(self, req, output_dir, python_tag=None):
         """Build one wheel.
 
         :return: The filename of the built wheel, or None if the build failed.
         """
-        build_reqs, isolate = req.get_pep_518_info()
-        if 'setuptools' not in build_reqs:
-            logger.warning(
-                "This version of pip does not implement PEP 516, so "
-                "it cannot build a wheel without setuptools. You may need to "
-                "upgrade to a newer version of pip.")
         # Install build deps into temporary directory (PEP 518)
-            self._install_build_reqs(build_reqs, prefix)
         with req.build_environment as prefix:
             return self._build_one_inside_env(req, output_dir,
                                               python_tag=python_tag,

From 8dad780026ab70071c2247535e1df8007a40ed7a Mon Sep 17 00:00:00 2001
From: xoviat <xoviat@users.noreply.github.com>
Date: Sat, 27 Jan 2018 11:04:43 -0600
Subject: [PATCH 07/18] Address review comments

---
 src/pip/_internal/build_env.py          |  2 +-
 src/pip/_internal/operations/prepare.py | 11 ++++++-----
 src/pip/_internal/req/req_install.py    |  4 ++--
 src/pip/_internal/resolve.py            |  2 +-
 4 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/src/pip/_internal/build_env.py b/src/pip/_internal/build_env.py
index 97ec00aa6fb..5a2abf6defa 100644
--- a/src/pip/_internal/build_env.py
+++ b/src/pip/_internal/build_env.py
@@ -67,7 +67,7 @@ def cleanup(self):
         self._temp_dir.cleanup()
 
 
-class FakeBuildEnvironment(BuildEnvironment):
+class NoOpBuildEnvironment(BuildEnvironment):
     def __enter__(self):
         pass
 
diff --git a/src/pip/_internal/operations/prepare.py b/src/pip/_internal/operations/prepare.py
index 837c8f7a7d8..7b7b734d45c 100644
--- a/src/pip/_internal/operations/prepare.py
+++ b/src/pip/_internal/operations/prepare.py
@@ -25,7 +25,7 @@
 from pip._internal.vcs import vcs
 from pip._internal.req.req_install import InstallRequirement
 from pip._internal.index import FormatControl
-from pip._internal.build_env import FakeBuildEnvironment
+from pip._internal.build_env import NoOpBuildEnvironment
 
 logger = logging.getLogger(__name__)
 
@@ -113,6 +113,9 @@ def dist(self, finder):
         return dist
 
     def prep_for_dist(self, finder):
+        # Before calling "setup.py egg_info", we need to set-up the build
+        # environment.
+        
         build_requirements, isolate = self.req.get_pep_518_info()
 
         if 'setuptools' not in build_requirements:
@@ -122,11 +125,9 @@ def prep_for_dist(self, finder):
                 "upgrade to a newer version of pip.")
 
         if not isolate:
-            self.req.build_environment = FakeBuildEnvironment(no_clean=False)
+            self.req.build_env = NoOpBuildEnvironment(no_clean=False)
 
-        with self.req.build_environment as prefix:
-            # Ignore the --no-binary option when installing the build system, so
-            # we don't recurse trying to build a self-hosting build system.
+        with self.req.build_env as prefix:
             if isolate:
                 _install_build_reqs(finder, prefix, build_requirements)
 
diff --git a/src/pip/_internal/req/req_install.py b/src/pip/_internal/req/req_install.py
index ed7e20b5476..c81a6ff3818 100644
--- a/src/pip/_internal/req/req_install.py
+++ b/src/pip/_internal/req/req_install.py
@@ -129,7 +129,7 @@ def __init__(self, req, comes_from, source_dir=None, editable=False,
         self.prepared = False
 
         self.isolated = isolated
-        self.build_environment = BuildEnvironment(no_clean=True)
+        self.build_env = BuildEnvironment(no_clean=True)
 
     @classmethod
     def from_editable(cls, editable_req, comes_from=None, isolated=False,
@@ -882,7 +882,7 @@ def remove_temporary_source(self):
             rmtree(self.source_dir)
         self.source_dir = None
         self._temp_build_dir.cleanup()
-        self.build_environment.cleanup()
+        self.build_env.cleanup()
 
     def install_editable(self, install_options,
                          global_options=(), prefix=None):
diff --git a/src/pip/_internal/resolve.py b/src/pip/_internal/resolve.py
index 850af7a6f10..22756fd3a44 100644
--- a/src/pip/_internal/resolve.py
+++ b/src/pip/_internal/resolve.py
@@ -187,7 +187,7 @@ def _get_abstract_dist_for(self, req):
 
         if req.editable:
             return self.preparer.prepare_editable_requirement(
-                req, self.require_hashes, self.finder
+                req, self.require_hashes, self.finder,
             )
 
         # satisfied_by is only evaluated by calling _check_skip_installed,

From d3d13eaab71be592e7da544939561c19ded2fdbe Mon Sep 17 00:00:00 2001
From: xoviat <xoviat@users.noreply.github.com>
Date: Sat, 27 Jan 2018 11:07:19 -0600
Subject: [PATCH 08/18] :art:

---
 src/pip/_internal/build_env.py          |  2 +-
 src/pip/_internal/operations/prepare.py | 16 ++++++++++------
 src/pip/_internal/resolve.py            |  4 +++-
 3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/src/pip/_internal/build_env.py b/src/pip/_internal/build_env.py
index 5a2abf6defa..1819105fa83 100644
--- a/src/pip/_internal/build_env.py
+++ b/src/pip/_internal/build_env.py
@@ -73,6 +73,6 @@ def __enter__(self):
 
     def __exit__(self, exc_type, exc_val, exc_tb):
         pass
-        
+
     def cleanup(self):
         pass
diff --git a/src/pip/_internal/operations/prepare.py b/src/pip/_internal/operations/prepare.py
index 7b7b734d45c..ea4442847b3 100644
--- a/src/pip/_internal/operations/prepare.py
+++ b/src/pip/_internal/operations/prepare.py
@@ -49,11 +49,15 @@ def make_abstract_dist(req):
 def _install_build_reqs(finder, prefix, build_requirements):
     finder = copy(finder)
     finder.format_control = FormatControl(set(), set([":all:"]))
-    urls = [finder.find_requirement(InstallRequirement.from_line(r),
-                                    upgrade=False).url
-            for r in build_requirements]
-    args = [sys.executable, '-m', 'pip', 'install', '--ignore-installed',
-        '--prefix', prefix] + list(urls)
+    urls = [
+        finder.find_requirement(
+            InstallRequirement.from_line(r), upgrade=False).url
+        for r in build_requirements
+    ]
+    args = [
+        sys.executable, '-m', 'pip', 'install', '--ignore-installed',
+        '--prefix', prefix
+    ] + list(urls)
 
     with open_spinner("Installing build dependencies") as spinner:
         call_subprocess(args, show_stdout=False, spinner=spinner)
@@ -115,7 +119,7 @@ def dist(self, finder):
     def prep_for_dist(self, finder):
         # Before calling "setup.py egg_info", we need to set-up the build
         # environment.
-        
+
         build_requirements, isolate = self.req.get_pep_518_info()
 
         if 'setuptools' not in build_requirements:
diff --git a/src/pip/_internal/resolve.py b/src/pip/_internal/resolve.py
index 22756fd3a44..d7b5ab0eea3 100644
--- a/src/pip/_internal/resolve.py
+++ b/src/pip/_internal/resolve.py
@@ -187,7 +187,9 @@ def _get_abstract_dist_for(self, req):
 
         if req.editable:
             return self.preparer.prepare_editable_requirement(
-                req, self.require_hashes, self.finder,
+                req,
+                self.require_hashes,
+                self.finder,
             )
 
         # satisfied_by is only evaluated by calling _check_skip_installed,

From 3b88968f0da0b9cd4385b9af5c51ffc1bb30ccd4 Mon Sep 17 00:00:00 2001
From: xoviat <xoviat@users.noreply.github.com>
Date: Sat, 27 Jan 2018 11:11:02 -0600
Subject: [PATCH 09/18] :art:

---
 src/pip/_internal/operations/prepare.py | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/pip/_internal/operations/prepare.py b/src/pip/_internal/operations/prepare.py
index ea4442847b3..6e0879df4c0 100644
--- a/src/pip/_internal/operations/prepare.py
+++ b/src/pip/_internal/operations/prepare.py
@@ -1,15 +1,15 @@
 """Prepares a distribution for installation
 """
 
+import itertools
 import logging
 import os
 import sys
-import itertools
-
 from copy import copy
 
 from pip._vendor import pkg_resources, requests
 
+from pip._internal.build_env import NoOpBuildEnvironment
 from pip._internal.compat import expanduser
 from pip._internal.download import (
     is_dir_url, is_file_url, is_vcs_url, unpack_url, url_to_path,
@@ -18,14 +18,15 @@
     DirectoryUrlHashUnsupported, HashUnpinned, InstallationError,
     PreviousBuildDirError, VcsHashUnsupported,
 )
+from pip._internal.index import FormatControl
+from pip._internal.req.req_install import InstallRequirement
 from pip._internal.utils.hashes import MissingHashes
 from pip._internal.utils.logging import indent_log
-from pip._internal.utils.misc import display_path, normalize_path, call_subprocess
+from pip._internal.utils.misc import (
+    call_subprocess, display_path, normalize_path,
+)
 from pip._internal.utils.ui import open_spinner
 from pip._internal.vcs import vcs
-from pip._internal.req.req_install import InstallRequirement
-from pip._internal.index import FormatControl
-from pip._internal.build_env import NoOpBuildEnvironment
 
 logger = logging.getLogger(__name__)
 

From 74c086bd2b0f24af4ab66128271de069de31bb63 Mon Sep 17 00:00:00 2001
From: xoviat <xoviat@users.noreply.github.com>
Date: Sat, 27 Jan 2018 11:14:04 -0600
Subject: [PATCH 10/18] :art:

---
 src/pip/_internal/wheel.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/pip/_internal/wheel.py b/src/pip/_internal/wheel.py
index a5ac3b63642..9dca5baae76 100644
--- a/src/pip/_internal/wheel.py
+++ b/src/pip/_internal/wheel.py
@@ -623,7 +623,7 @@ def _build_one(self, req, output_dir, python_tag=None):
         :return: The filename of the built wheel, or None if the build failed.
         """
         # Install build deps into temporary directory (PEP 518)
-        with req.build_environment as prefix:
+        with req.build_environment:
             return self._build_one_inside_env(req, output_dir,
                                               python_tag=python_tag,
                                               isolate=True)

From 5bb4e7611936b92a7e7558f51007576f2070c9c0 Mon Sep 17 00:00:00 2001
From: xoviat <xoviat@users.noreply.github.com>
Date: Sat, 27 Jan 2018 11:17:04 -0600
Subject: [PATCH 11/18] :news:

---
 news/4799.bugfix | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 news/4799.bugfix

diff --git a/news/4799.bugfix b/news/4799.bugfix
new file mode 100644
index 00000000000..782f70a9301
--- /dev/null
+++ b/news/4799.bugfix
@@ -0,0 +1 @@
+Fix situation where build requirements are installed before calling setup.py.
\ No newline at end of file

From b2144259f0b3bea6d138ffa47ade39f9a27901ad Mon Sep 17 00:00:00 2001
From: xoviat <xoviat@users.noreply.github.com>
Date: Sat, 27 Jan 2018 11:27:19 -0600
Subject: [PATCH 12/18] Add regression test

---
 tests/data/packages/pep518-3.0.tar.gz | Bin 832 -> 851 bytes
 tests/data/src/pep518-3.0/setup.py    |   2 ++
 2 files changed, 2 insertions(+)

diff --git a/tests/data/packages/pep518-3.0.tar.gz b/tests/data/packages/pep518-3.0.tar.gz
index cfd03320375ad458026502c95660c407ff594098..08cc3887550e992da3bca1605c4e894303a19544 100644
GIT binary patch
delta 848
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delta 826
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diff --git a/tests/data/src/pep518-3.0/setup.py b/tests/data/src/pep518-3.0/setup.py
index f9d4c48913d..c44e35fdd06 100644
--- a/tests/data/src/pep518-3.0/setup.py
+++ b/tests/data/src/pep518-3.0/setup.py
@@ -1,6 +1,8 @@
 #!/usr/bin/env python
 from setuptools import find_packages, setup
 
+import simple  # Test gh-4647 regression
+
 setup(name='pep518',
       version='3.0',
       packages=find_packages()

From 12202eecde9f4ac3c0109e27eb21fc63f60bbf98 Mon Sep 17 00:00:00 2001
From: xoviat <xoviat@users.noreply.github.com>
Date: Sat, 27 Jan 2018 11:28:23 -0600
Subject: [PATCH 13/18] Fix regression

---
 src/pip/_internal/wheel.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/pip/_internal/wheel.py b/src/pip/_internal/wheel.py
index 9dca5baae76..17d52911698 100644
--- a/src/pip/_internal/wheel.py
+++ b/src/pip/_internal/wheel.py
@@ -623,7 +623,7 @@ def _build_one(self, req, output_dir, python_tag=None):
         :return: The filename of the built wheel, or None if the build failed.
         """
         # Install build deps into temporary directory (PEP 518)
-        with req.build_environment:
+        with req.build_env:
             return self._build_one_inside_env(req, output_dir,
                                               python_tag=python_tag,
                                               isolate=True)

From 5c77300ce86232f9e756173f3655e3a2ad512a05 Mon Sep 17 00:00:00 2001
From: xoviat <xoviat@users.noreply.github.com>
Date: Sat, 27 Jan 2018 11:41:56 -0600
Subject: [PATCH 14/18] Fix regression test

---
 tests/data/packages/pep518-3.0.tar.gz    | Bin 851 -> 853 bytes
 tests/data/src/pep518-3.0/pyproject.toml |   2 +-
 2 files changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/data/packages/pep518-3.0.tar.gz b/tests/data/packages/pep518-3.0.tar.gz
index 08cc3887550e992da3bca1605c4e894303a19544..f912e6d85a2e689bb46f266d6571fbbf8714a36a 100644
GIT binary patch
delta 847
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Zf&T=PF#{G3004m3$Zx(Bpzi=s004$&yW#)<

delta 843
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zt)WvYB${67mSednp;Kik@~n}MEiT&Ns=(;4m$PqutF57eSy^cG*VTNSx8B~cfA97+
z8=JTNn~;W9qW^M}wN;D$pZ5KSiB%ea?>}B7{;S_)f9(G6y#BKcVnF_HB>#`oFw7u-
V0+TTV7!1H`<TvtBf6xF>008W8z-Ryf

diff --git a/tests/data/src/pep518-3.0/pyproject.toml b/tests/data/src/pep518-3.0/pyproject.toml
index 5e3bb233223..b51a1cec7c7 100644
--- a/tests/data/src/pep518-3.0/pyproject.toml
+++ b/tests/data/src/pep518-3.0/pyproject.toml
@@ -1,2 +1,2 @@
 [build-system]
-requires=["simple==3.0", "setuptools", "wheel"]
+requires=["simplewheel==2.0", "setuptools", "wheel"]

From 88105000f59624a38ce6dca86c08c6e623ba4850 Mon Sep 17 00:00:00 2001
From: xoviat <xoviat@users.noreply.github.com>
Date: Sat, 27 Jan 2018 14:37:43 -0600
Subject: [PATCH 15/18] Address review

---
 news/4799.bugfix                   | 1 -
 news/4799.trivial                  | 0
 src/pip/_internal/build_env.py     | 3 +++
 tests/data/src/pep518-3.0/setup.py | 2 +-
 4 files changed, 4 insertions(+), 2 deletions(-)
 delete mode 100644 news/4799.bugfix
 create mode 100644 news/4799.trivial

diff --git a/news/4799.bugfix b/news/4799.bugfix
deleted file mode 100644
index 782f70a9301..00000000000
--- a/news/4799.bugfix
+++ /dev/null
@@ -1 +0,0 @@
-Fix situation where build requirements are installed before calling setup.py.
\ No newline at end of file
diff --git a/news/4799.trivial b/news/4799.trivial
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/src/pip/_internal/build_env.py b/src/pip/_internal/build_env.py
index 1819105fa83..6364aacecda 100644
--- a/src/pip/_internal/build_env.py
+++ b/src/pip/_internal/build_env.py
@@ -68,6 +68,9 @@ def cleanup(self):
 
 
 class NoOpBuildEnvironment(BuildEnvironment):
+    def __init__(self, no_clean):
+        pass
+
     def __enter__(self):
         pass
 
diff --git a/tests/data/src/pep518-3.0/setup.py b/tests/data/src/pep518-3.0/setup.py
index c44e35fdd06..84e7feb702d 100644
--- a/tests/data/src/pep518-3.0/setup.py
+++ b/tests/data/src/pep518-3.0/setup.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python
 from setuptools import find_packages, setup
 
-import simple  # Test gh-4647 regression
+import simple  # ensure dependency is installed
 
 setup(name='pep518',
       version='3.0',

From 1601ebb6f9e02c836103c9c7e2017bbef895172d Mon Sep 17 00:00:00 2001
From: xoviat <xoviat@users.noreply.github.com>
Date: Sat, 27 Jan 2018 14:38:19 -0600
Subject: [PATCH 16/18] revert .gitignore

---
 .gitignore | 1 -
 1 file changed, 1 deletion(-)

diff --git a/.gitignore b/.gitignore
index 6894e3376df..1d842203ba8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -36,4 +36,3 @@ coverage.xml
 
 # Scratch Pad for experiments
 .scratch/
-.vscode
\ No newline at end of file

From 14ae49d6da69da1b4a475704f5992bd0bbb1853b Mon Sep 17 00:00:00 2001
From: Pradyun Gedam <pradyunsg@gmail.com>
Date: Thu, 1 Mar 2018 12:12:26 +0530
Subject: [PATCH 17/18] :pencil2: Add a note + docstring

---
 src/pip/_internal/build_env.py          | 5 ++++-
 src/pip/_internal/operations/prepare.py | 3 +++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/pip/_internal/build_env.py b/src/pip/_internal/build_env.py
index 6364aacecda..1989c8aad05 100644
--- a/src/pip/_internal/build_env.py
+++ b/src/pip/_internal/build_env.py
@@ -8,7 +8,7 @@
 
 
 class BuildEnvironment(object):
-    """Manages a temporary environment to install build deps
+    """Creates and manages an isolated environment to install build deps
     """
 
     def __init__(self, no_clean):
@@ -68,6 +68,9 @@ def cleanup(self):
 
 
 class NoOpBuildEnvironment(BuildEnvironment):
+    """A no-op drop-in replacement for BuildEnvironment
+    """
+
     def __init__(self, no_clean):
         pass
 
diff --git a/src/pip/_internal/operations/prepare.py b/src/pip/_internal/operations/prepare.py
index 6e0879df4c0..0fbc0ecd233 100644
--- a/src/pip/_internal/operations/prepare.py
+++ b/src/pip/_internal/operations/prepare.py
@@ -48,6 +48,9 @@ def make_abstract_dist(req):
 
 
 def _install_build_reqs(finder, prefix, build_requirements):
+    # NOTE: What follows is not a very good thing.
+    #       Eventually, this should move into the BuildEnvironment class and
+    #       that should handle all the isolation and sub-process invocation.
     finder = copy(finder)
     finder.format_control = FormatControl(set(), set([":all:"]))
     urls = [

From 5e16d5105eac107db5c8eca7ff776f754ce0262b Mon Sep 17 00:00:00 2001
From: Pradyun Gedam <pradyunsg@gmail.com>
Date: Thu, 1 Mar 2018 12:12:31 +0530
Subject: [PATCH 18/18] :art:

---
 src/pip/_internal/operations/prepare.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/pip/_internal/operations/prepare.py b/src/pip/_internal/operations/prepare.py
index 0fbc0ecd233..86e2e7b9954 100644
--- a/src/pip/_internal/operations/prepare.py
+++ b/src/pip/_internal/operations/prepare.py
@@ -60,7 +60,7 @@ def _install_build_reqs(finder, prefix, build_requirements):
     ]
     args = [
         sys.executable, '-m', 'pip', 'install', '--ignore-installed',
-        '--prefix', prefix
+        '--prefix', prefix,
     ] + list(urls)
 
     with open_spinner("Installing build dependencies") as spinner: