Investigate crash while committing.

[knmorgan]

Problem committing to 'repo', error was '['git', 'tag', 'v1.2', 'HEAD']'
Traceback (most recent call last):
  File "/home/mjeg/Documents/Work/rackspace/repos/tina/tina/tina.py", line 100, in <module>
    main()
  File "/home/mjeg/Documents/Work/rackspace/repos/tina/tina/tina.py", line 97, in main
    commit_and_push(git.Repo(".tina/%s" % repo_name), repo_name)
  File "/home/mjeg/Documents/Work/rackspace/repos/tina/tina/GitLib.py", line 54, in commit_and_push
    create_tag(repo, tag)
  File "/home/mjeg/Documents/Work/rackspace/repos/tina/tina/GitLib.py", line 47, in create_tag
    repo.create_tag('v' + tag_num)
  File "/usr/lib64/python2.7/site-packages/GitPython-0.3.2.RC1-py2.7.egg/git/repo/base.py", line 300, in create_tag
    return TagReference.create(self, path, ref, message, force, **kwargs)
  File "/usr/lib64/python2.7/site-packages/GitPython-0.3.2.RC1-py2.7.egg/git/refs/tag.py", line 80, in create
    repo.git.tag(*args, **kwargs)
  File "/usr/lib64/python2.7/site-packages/GitPython-0.3.2.RC1-py2.7.egg/git/cmd.py", line 227, in <lambda>
    return lambda *args, **kwargs: self._call_process(name, *args, **kwargs)
  File "/usr/lib64/python2.7/site-packages/GitPython-0.3.2.RC1-py2.7.egg/git/cmd.py", line 456, in _call_process
    return self.execute(call, **_kwargs)
  File "/usr/lib64/python2.7/site-packages/GitPython-0.3.2.RC1-py2.7.egg/git/cmd.py", line 377, in execute
    raise GitCommandError(command, status, stderr_value)
git.exc.GitCommandError: 'git tag v1.2 HEAD' returned exit status 128: fatal: tag 'v1.2' already exists

[knmorgan]

Fixed as part of dfc1c9b.