We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
No module named 'six'
Flask's Tox/Travis builds all started failing. Looks like a new version of setuptools was just released that has a problem with six.

~~~pytb
Obtaining file:///home/david/Projects/flask
Installing collected packages: Flask
  Running setup.py develop for Flask
    Complete output from command /home/david/Projects/flask/.tox/py/bin/python3 -c "import setuptools, tokenize;__file__='/home/david/Projects/flask/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" develop --no-deps:
    /home/david/Projects/flask/.tox/py/lib/python3.6/site-packages/setuptools/dist.py:336: UserWarning: Normalizing '0.13-dev' to '0.13.dev0'
      normalized_version,
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/home/david/Projects/flask/setup.py", line 109, in <module>
        '''
      File "/usr/lib64/python3.6/distutils/core.py", line 134, in setup
        ok = dist.parse_command_line()
      File "/home/david/Projects/flask/.tox/py/lib/python3.6/site-packages/setuptools/dist.py", line 363, in parse_command_line
        result = _Distribution.parse_command_line(self)
      File "/usr/lib64/python3.6/distutils/dist.py", line 472, in parse_command_line
        args = self._parse_command_opts(parser, args)
      File "/home/david/Projects/flask/.tox/py/lib/python3.6/site-packages/setuptools/dist.py", line 674, in _parse_command_opts
        nargs = _Distribution._parse_command_opts(self, parser, args)
      File "/usr/lib64/python3.6/distutils/dist.py", line 528, in _parse_command_opts
        cmd_class = self.get_command_class(command)
      File "/home/david/Projects/flask/.tox/py/lib/python3.6/site-packages/setuptools/dist.py", line 495, in get_command_class
        self.cmdclass[command] = cmdclass = ep.load()
      File "/home/david/Projects/flask/.tox/py/lib/python3.6/site-packages/pkg_resources/__init__.py", line 2303, in load
        return self.resolve()
      File "/home/david/Projects/flask/.tox/py/lib/python3.6/site-packages/pkg_resources/__init__.py", line 2309, in resolve
        module = __import__(self.module_name, fromlist=['__name__'], level=0)
      File "/home/david/Projects/flask/.tox/py/lib/python3.6/site-packages/setuptools/command/develop.py", line 11, in <module>
        from setuptools.command.easy_install import easy_install
      File "/home/david/Projects/flask/.tox/py/lib/python3.6/site-packages/setuptools/command/easy_install.py", line 49, in <module>
        from setuptools.py27compat import rmtree_safe
      File "/home/david/Projects/flask/.tox/py/lib/python3.6/site-packages/setuptools/py27compat.py", line 7, in <module>
        import six
    ModuleNotFoundError: No module named 'six'
~~~

Example failed build log: https://travis-ci.org/pallets/flask/jobs/238166427#L242

--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `setuptools/py27compat.py`
Content:
```
1 """
2 Compatibility Support for Python 2.7 and earlier
3 """
4 
5 import platform
6 
7 import six
8 
9 
10 def get_all_headers(message, key):
11     """
12     Given an HTTPMessage, return all headers matching a given key.
13     """
14     return message.get_all(key)
15 
16 
17 if six.PY2:
18     def get_all_headers(message, key):
19         return message.getheaders(key)
20 
21 
22 linux_py2_ascii = (
23     platform.system() == 'Linux' and
24     six.PY2
25 )
26 
27 rmtree_safe = str if linux_py2_ascii else lambda x: x
28 """Workaround for http://bugs.python.org/issue24672"""
29
```
--- END FILES ---

Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.

Here is an example:

```diff
diff --git a/examples/server_async.py b/examples/server_async.py
--- a/examples/server_async.py
+++ b/examples/server_async.py
@@ -313,4 +313,4 @@
 
 
 if __name__ == "__main__":
-    asyncio.run(run_async_server("."), debug=True)
+    asyncio.run(run_async_server(), debug=True)
diff --git a/examples/server_sync.py b/examples/server_sync.py
--- a/examples/server_sync.py
+++ b/examples/server_sync.py
@@ -313,5 +313,5 @@
 
 
 if __name__ == "__main__":
-    server = run_sync_server(".")
+    server = run_sync_server()
     server.shutdown()

```

diff --git a/setuptools/py27compat.py b/setuptools/py27compat.py
--- a/setuptools/py27compat.py
+++ b/setuptools/py27compat.py
@@ -4,7 +4,7 @@
 
 import platform
 
-import six
+from setuptools.extern import six
 
 
 def get_all_headers(message, key):

{"golden_diff": "diff --git a/setuptools/py27compat.py b/setuptools/py27compat.py\n--- a/setuptools/py27compat.py\n+++ b/setuptools/py27compat.py\n@@ -4,7 +4,7 @@\n \n import platform\n \n-import six\n+from setuptools.extern import six\n \n \n def get_all_headers(message, key):\n", "issue": "No module named 'six'\nFlask's Tox/Travis builds all started failing. Looks like a new version of setuptools was just released that has a problem with six.\r\n\r\n~~~pytb\r\nObtaining file:///home/david/Projects/flask\r\nInstalling collected packages: Flask\r\n  Running setup.py develop for Flask\r\n    Complete output from command /home/david/Projects/flask/.tox/py/bin/python3 -c \"import setuptools, tokenize;__file__='/home/david/Projects/flask/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\\r\\n', '\\n');f.close();exec(compile(code, __file__, 'exec'))\" develop --no-deps:\r\n    /home/david/Projects/flask/.tox/py/lib/python3.6/site-packages/setuptools/dist.py:336: UserWarning: Normalizing '0.13-dev' to '0.13.dev0'\r\n      normalized_version,\r\n    Traceback (most recent call last):\r\n      File \"<string>\", line 1, in <module>\r\n      File \"/home/david/Projects/flask/setup.py\", line 109, in <module>\r\n        '''\r\n      File \"/usr/lib64/python3.6/distutils/core.py\", line 134, in setup\r\n        ok = dist.parse_command_line()\r\n      File \"/home/david/Projects/flask/.tox/py/lib/python3.6/site-packages/setuptools/dist.py\", line 363, in parse_command_line\r\n        result = _Distribution.parse_command_line(self)\r\n      File \"/usr/lib64/python3.6/distutils/dist.py\", line 472, in parse_command_line\r\n        args = self._parse_command_opts(parser, args)\r\n      File \"/home/david/Projects/flask/.tox/py/lib/python3.6/site-packages/setuptools/dist.py\", line 674, in _parse_command_opts\r\n        nargs = _Distribution._parse_command_opts(self, parser, args)\r\n      File \"/usr/lib64/python3.6/distutils/dist.py\", line 528, in _parse_command_opts\r\n        cmd_class = self.get_command_class(command)\r\n      File \"/home/david/Projects/flask/.tox/py/lib/python3.6/site-packages/setuptools/dist.py\", line 495, in get_command_class\r\n        self.cmdclass[command] = cmdclass = ep.load()\r\n      File \"/home/david/Projects/flask/.tox/py/lib/python3.6/site-packages/pkg_resources/__init__.py\", line 2303, in load\r\n        return self.resolve()\r\n      File \"/home/david/Projects/flask/.tox/py/lib/python3.6/site-packages/pkg_resources/__init__.py\", line 2309, in resolve\r\n        module = __import__(self.module_name, fromlist=['__name__'], level=0)\r\n      File \"/home/david/Projects/flask/.tox/py/lib/python3.6/site-packages/setuptools/command/develop.py\", line 11, in <module>\r\n        from setuptools.command.easy_install import easy_install\r\n      File \"/home/david/Projects/flask/.tox/py/lib/python3.6/site-packages/setuptools/command/easy_install.py\", line 49, in <module>\r\n        from setuptools.py27compat import rmtree_safe\r\n      File \"/home/david/Projects/flask/.tox/py/lib/python3.6/site-packages/setuptools/py27compat.py\", line 7, in <module>\r\n        import six\r\n    ModuleNotFoundError: No module named 'six'\r\n~~~\r\n\r\nExample failed build log: https://travis-ci.org/pallets/flask/jobs/238166427#L242\n", "before_files": [{"content": "\"\"\"\nCompatibility Support for Python 2.7 and earlier\n\"\"\"\n\nimport platform\n\nimport six\n\n\ndef get_all_headers(message, key):\n    \"\"\"\n    Given an HTTPMessage, return all headers matching a given key.\n    \"\"\"\n    return message.get_all(key)\n\n\nif six.PY2:\n    def get_all_headers(message, key):\n        return message.getheaders(key)\n\n\nlinux_py2_ascii = (\n    platform.system() == 'Linux' and\n    six.PY2\n)\n\nrmtree_safe = str if linux_py2_ascii else lambda x: x\n\"\"\"Workaround for http://bugs.python.org/issue24672\"\"\"\n", "path": "setuptools/py27compat.py"}], "after_files": [{"content": "\"\"\"\nCompatibility Support for Python 2.7 and earlier\n\"\"\"\n\nimport platform\n\nfrom setuptools.extern import six\n\n\ndef get_all_headers(message, key):\n    \"\"\"\n    Given an HTTPMessage, return all headers matching a given key.\n    \"\"\"\n    return message.get_all(key)\n\n\nif six.PY2:\n    def get_all_headers(message, key):\n        return message.getheaders(key)\n\n\nlinux_py2_ascii = (\n    platform.system() == 'Linux' and\n    six.PY2\n)\n\nrmtree_safe = str if linux_py2_ascii else lambda x: x\n\"\"\"Workaround for http://bugs.python.org/issue24672\"\"\"\n", "path": "setuptools/py27compat.py"}]}