I noticed that matplotlib does not include Python 3.2 in its Travis build, but includes wheels for Python 3.2.
Scikit image has a 3.2 Travis build, and stopped working this week. We traced the problem to a timeout during pip install matplotlib. It prints the config output and then hangs indefinitely (at least 44 minutes). When we instead use pip install matplotlib==1.3.1, the install proceeds as usual.

Failing build: https://travis-ci.org/blink1073/scikit-image/jobs/34035724