This test is waaay to slow (about the same time as the next 4 slowest tests together, which are also too slow):
Travis says

64.80s call     sklearn/cluster/tests/test_mean_shift.py::test_parallel

The core of the tests doesn't seem like it has been touched since #5189 by @GaelVaroquaux but I don't remember the test being so slow back then (I'll confirm though).