This should be a merge of master branch in f18 branch of pytz and then submit; but this updates the pytz version. This request due to https://bugzilla.redhat.com/show_bug.cgi?id=837156#c44 Another option I have is to build python3-matplotlib with it's bundled pytz copy. I think just adapting the patch from https://bugzilla.redhat.com/show_bug.cgi?id=851226 should do it, and not need to update pytz version in f18.
I was toying a bit with adding python3 support on f18 package but it does not work (also by mistake typed "fedpkg build" instead of "fedpkg local" when doing a last test in rawhide instead of fedpkg mockbuild for f18...) So, it appears the only clean way to add python3 support would be to upgrade to the rawhide version; I tried start patching, but would require a significant amount of patches.
pytz-2012d-2.fc18 has been submitted as an update for Fedora 18. https://admin.fedoraproject.org/updates/pytz-2012d-2.fc18
pytz-2012d-2.fc18 has been pushed to the Fedora 18 stable repository. If problems still persist, please make note of it in this bug report.