app-vim/python-mode depends on pep8, which has recently changed its internal API in a way that may (or may not) affect python-mode. Please check if python-mode is compatible with pep8 1.3 and adjust dependencies as needed. Thank you!
It uses {auto,}pep8 as an external tool so doesn't care about API. It actually bundles both of them, but I force it to use system ones. Thanks!