git-upstream doesn't work with gitpython-2.0.9

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2016-10-17.09:57 desbonne@kilcolgan2:~/src/review.hpcloud.net/openstack/python-novaclient$ pip freeze | grep -i git
  git-upstream==0.11.0
  gitdb2==2.0.0
  GitPython==2.0.9
  2016-10-17.09:57 desbonne@kilcolgan2:~/src/review.hpcloud.net/openstack/python-novaclient$ git-upstream import --into hp/prerelease/newton stable/newton
  Traceback (most recent call last):
    File "/tmp/with_workspace.37QzIZ/_workspace_venv/bin/git-upstream", line 11, in <module>
      sys.exit(main())
    File "/tmp/with_workspace.37QzIZ/_workspace_venv/local/lib/python2.7/site-packages/git_upstream/main.py", line 142, in main
      args.cmd.run(args)
    File "/tmp/with_workspace.37QzIZ/_workspace_venv/local/lib/python2.7/site-packages/git_upstream/commands/__init__.py", line 71, in run
      return self.execute()
    File "/tmp/with_workspace.37QzIZ/_workspace_venv/local/lib/python2.7/site-packages/git_upstream/commands/import.py", line 145, in execute
      extra_branches=self.args.branches)
    File "/tmp/with_workspace.37QzIZ/_workspace_venv/local/lib/python2.7/site-packages/git_upstream/lib/importupstream.py", line 48, in __init__
      super(ImportUpstream, self).__init__(*args, **kwargs)
    File "/tmp/with_workspace.37QzIZ/_workspace_venv/local/lib/python2.7/site-packages/git_upstream/log.py", line 154, in __init__
      super(LogDedentMixin, self).__init__(*args, **kwargs)
    File "/tmp/with_workspace.37QzIZ/_workspace_venv/local/lib/python2.7/site-packages/git_upstream/lib/utils.py", line 39, in __init__
      os.path.curdir))
    File "/tmp/with_workspace.37QzIZ/_workspace_venv/local/lib/python2.7/site-packages/git/repo/base.py", line 146, in __init__
      self.git_dir = None
  AttributeError: can't set attribute

Looks like due to the _GitUpstreamCompatRepo_ class being wrapped around the git.Repo class. Latest gitpython-2.0.9 drops the __slots__ attribute from the base repo class which breaks the hasattr test in pygitcompat.py

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/387342

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/387342
Committed: https://git.openstack.org/cgit/openstack/git-upstream/commit/?id=5c0a4a7e4d56a8301e7391abf0bb79d387a98ae1
Submitter: Jenkins
Branch: master

commit 5c0a4a7e4d56a8301e7391abf0bb79d387a98ae1
Author: Darragh Bailey <email address hidden>
Date: Mon Oct 17 11:26:44 2016 +0100

    Remove compatibility hacks causing issues with newer GitPython

    Remove some monkey patching used to allow git-upstream to work with
    GitPython releases older than 0.3.2, as the project requirements now
    depends on 1.0.1 or newer.

    GitPython release from 2.0.9 onwards removes the '__slots__'
    definition. This allowed for the git_dir attribute existence to be
    checked to determine whether to patch the Commit class imported from
    the GitPython project to add this attribute for older versions of the
    API.

    Change-Id: I3d83785b16cd0650942c7112b5cafffc21dddba7
    Closes-Bug: #1634053