I believe polib provided by the current python-polib rpm supports both python2 and python3. However, the rpm only provides source in the python2.7/site-packages directory and there is no python3-polib rpm.
I don't know the correct way to handle these types of packages, but should the polib rpm be updated to place symlinks of the polib files from the python2.7/site-packages to python3.2/site-packages? Or should a python3-polib rpm be created using the same source?
I've tested the symlink workaround by successfully building dupeguru (written in python3 and requiring polib). I don't have any specific experience with polib to test further.
 From the changelog from version 0.7: "This version adds support for python 3 (thanks to Vinay Sajip). polib now supports out-of-the-box any version of python ranging from 2.4 to latest 3.X version. polib is now 5 years old ;) so the 0.7.X branch will be the last before the 1.X stable branch."