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ERROR: test_diff_branch (monkey.git.GitBranchTest)
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Traceback (most recent call last):
  File "/tmp/testing/monkey/branch.py", line 77, in test_diff_branch
    diff = stripdiff(self.branch.diff_branch(copy))
  File "/tmp/testing/monkey/git.py", line 63, in diff_branch
    head = self._git('log', '-1', '--pretty=format:%H')
  File "/tmp/testing/monkey/git.py", line 26, in _git
    return _git(self.path, cmd, *args)
  File "/tmp/testing/monkey/git.py", line 22, in _git
    raise f
BranchOperationError: ('git-log', '-1', '--pretty=format:%H')