Fix PEXEnvironment platform determination.

Have this use pex intrinsics instead of pkg_resources which is known
to report bad values on Apple-shipped inerpreters.

Fixes pex-tool#523

pex/environment.py

@@ -120,13 +120,14 @@ def __init__(self, pex, pex_info, interpreter=None, **kw):
     self._interpreter = interpreter or PythonInterpreter.get()
     self._inherit_path = pex_info.inherit_path
     self._supported_tags = []
+
+    platform = Platform.current()
     super(PEXEnvironment, self).__init__(
       search_path=[] if pex_info.inherit_path == 'false' else sys.path,
+      platform=platform.platform,
       **kw
     )
-    self._supported_tags.extend(
-      Platform.create(self.platform).supported_tags(self._interpreter)
-    )
+    self._supported_tags.extend(platform.supported_tags(self._interpreter))
     TRACER.log(
       'E: tags for %r x %r -> %s' % (self.platform, self._interpreter, self._supported_tags),
       V=9

tests/test_environment.py

@@ -1,23 +1,34 @@
 # Copyright 2014 Pants project contributors (see CONTRIBUTORS.md).
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
-
 import os
+import platform
+import subprocess
 from contextlib import contextmanager
 
+import pytest
 from twitter.common.contextutil import temporary_dir
 
+from pex import resolver
 from pex.compatibility import nested
 from pex.environment import PEXEnvironment
+from pex.installer import EggInstaller, WheelInstaller
+from pex.interpreter import PythonInterpreter
+from pex.package import SourcePackage
+from pex.pex import PEX
 from pex.pex_builder import PEXBuilder
 from pex.pex_info import PexInfo
 from pex.testing import make_bdist, temporary_filename
 
 
 @contextmanager
-def yield_pex_builder(zip_safe=True):
-  with nested(temporary_dir(), make_bdist('p1', zipped=True, zip_safe=zip_safe)) as (td, p1):
-    pb = PEXBuilder(path=td)
-    pb.add_egg(p1.location)
+def yield_pex_builder(zip_safe=True, installer_impl=EggInstaller, interpreter=None):
+  with nested(temporary_dir(),
+              make_bdist('p1',
+                         zipped=True,
+                         zip_safe=zip_safe,
+                         installer_impl=installer_impl)) as (td, p1):
+    pb = PEXBuilder(path=td, interpreter=interpreter)
+    pb.add_dist_location(p1.location)
     yield pb
 
 
@@ -95,3 +106,30 @@ def test_load_internal_cache_unzipped():
     assert len(dists) == 1
     assert normalize(dists[0].location).startswith(
         normalize(os.path.join(pb.path(), pb.info.internal_cache)))
+
+
+_KNOWN_BAD_APPLE_INTERPRETER = ('/System/Library/Frameworks/Python.framework/Versions/'
+                                '2.7/Resources/Python.app/Contents/MacOS/Python')
+
+
+@pytest.mark.skipif(not os.path.exists(_KNOWN_BAD_APPLE_INTERPRETER),
+                    reason='Test requires known bad Apple interpreter {}'
+                           .format(_KNOWN_BAD_APPLE_INTERPRETER))
+def test_osx_platform_intel_issue_523():
+  interpreter = PythonInterpreter.from_binary(_KNOWN_BAD_APPLE_INTERPRETER)
+  with nested(yield_pex_builder(installer_impl=WheelInstaller, interpreter=interpreter),
+              temporary_filename()) as (pb, pex_file):
+    for dist in resolver.resolve(['psutil==5.4.7'], precedence=(SourcePackage,)):
+      pb.add_dist_location(dist.location)
+    pb.build(pex_file)
+
+    pex = PEX(pex_file, interpreter=interpreter)
+    args = ['-c', 'import pkg_resources; print(pkg_resources.get_supported_platform())']
+    process = pex.run(args=args, stdout=subprocess.PIPE, blocking=False)
+    stdout, _ = process.communicate()
+    assert 0 == process.returncode
+
+    # Verify this all worked under the previously problematic pkg_resources-reported platform.
+    release, _, _ = platform.mac_ver()
+    major_minor = '.'.join(release.split('.')[:2])
+    assert 'macosx-{}-intel'.format(major_minor) == stdout.strip()