Comment 1 for bug 48528

I'm getting the same problem.

I've checked out matplotlib, and in setup.py it tests for existence of pytz and dateutil in the system, and won't install them unless the user doesn't have them already. So I suspect that using python-tz as a build dependency and runtime dependency might fix the issue.

We're considering using matplotlib in a project, and this problem is affecting us, since zope3 depends on python-tz, and matplotlib currently breaks with python-tz installed, so we can't have both zope3 and matplotlib available at the same time.