I ran into this error as well and solved it differently in my PR, but I don't feel attached to either method. Python 2.6 needs one code path and 2.7 needs the other.

https://github.com/calebsmith/pybrightcove/blob/e086bb7ac661eaa541d1b52cc383fecd5fe8d6fc/tests/test_ftp_video.py#L91-L94

Rewriting this to not use .method_calls would probably be a better solution than either, but seems too time consuming to be worth it at this point, at least IMHO.