Ensure requirements-py2 is synced

PBR supports files of the style requirements-pyN where N is the
bundling python version, which means we need to sync the same number
of supported possible PBR files that can exist.

This adds in the missing py2 that was not being synced even though
it is a viable requirements file for PBR.

Fixes bug 1371936

Change-Id: I7956d77c275694cf09971766d16af054d2692261