Fixes --skip-existing with Nexus Repos

tests/test_upload.py

@@ -137,6 +137,20 @@ def test_skip_existing_skips_files_already_on_PyPI(monkeypatch):
                               package=pkg) is True
 
 
+def test_skip_existing_skips_files_already_on_nexus(monkeypatch):
+    # Nexus Repository Manager (https://www.sonatype.com/nexus-repository-oss)
+    # responds with 400 when the file already exists
+    response = pretend.stub(
+        status_code=400,
+        reason="Repository does not allow updating assets: pypi for url: "
+               "http://www.foo.bar")
+
+    pkg = package.PackageFile.from_filename(WHEEL_FIXTURE, None)
+    assert upload.skip_upload(response=response,
+                              skip_existing=True,
+                              package=pkg) is True
+
+
 def test_skip_existing_skips_files_already_on_pypiserver(monkeypatch):
     # pypiserver (https://pypi.org/project/pypiserver) responds with a
     # 409 when the file already exists.

twine/commands/upload.py

@@ -26,10 +26,14 @@
 
 def skip_upload(response, skip_existing, package):
     filename = package.basefilename
-    # NOTE(sigmavirus24): Old PyPI returns the first message while Warehouse
-    # returns the latter. This papers over the differences.
-    msg_400 = ('A file named "{0}" already exists for'.format(filename),
-               'File already exists')
+    msg_400 = (
+        # Old PyPI message:
+        'A file named "{0}" already exists for'.format(filename),
+        # Warehouse message:
+        'File already exists',
+        # Nexus Repository OSS message:
+        'Repository does not allow updating assets',
+    )
     msg_403 = 'Not enough permissions to overwrite artifact'
     # NOTE(sigmavirus24): PyPI presently returns a 400 status code with the
     # error message in the reason attribute. Other implementations return a
@@ -38,7 +42,7 @@ def skip_upload(response, skip_existing, package):
     #    True) AND
     # 2. a) The response status code is 409 OR
     # 2. b) The response status code is 400 AND it has a reason that matches
-    #       what we expect PyPI to return to us. OR
+    #       what we expect PyPI or Nexus OSS to return to us. OR
     # 2. c) The response status code is 403 AND the text matches what we
     #       expect Artifactory to return to us.
     return (skip_existing and (response.status_code == 409 or