Removing return that's outside a function.

Seeing the following error:

Traceback (most recent call last):
  File "/usr/local/bin/rebase-editor", line 6, in <module>
    from git_upstream.rebase_editor import main
  File "/usr/local/lib/python2.7/dist-packages/git_upstream-f1e2cc5-py2.7.egg/git_upstream/rebase_editor.py", line 126
    return main()
SyntaxError: 'return' outside function
Could not execute editor



I believe this fixes the issue.