Ugh. The reason Travis has been failing for Py2 is that another test was triggering the UserWarning for the bad unit cell dimensions and effectively disabling it from then on. Which means that when I ran the dummy box test by itself, it would work. But when I ran the whole test suite, it would fail (but only in Py2, which I don't really use anymore).
Ugh. The reason Travis has been failing for Py2 is that another test was
triggering the UserWarning for the bad unit cell dimensions and effectively
disabling it from then on. Which means that when I ran the dummy box test by
itself, it would work. But when I ran the whole test suite, it would fail (but
only in Py2, which I don't really use anymore).

This commit filters the warnings to *always* occur for the pdb module so this
can't happen.  But it only does it for Py2, because Py3 already does the right
thing (TM).

mpharrigan/mdtraj,swails/mdtraj,mpharrigan/mdtraj,mattwthompson/mdtraj,ctk3b/mdtraj,gph82/mdtraj,jchodera/mdtraj,mattwthompson/mdtraj,msultan/mdtraj,leeping/mdtraj,jchodera/mdtraj,ctk3b/mdtraj,mpharrigan/mdtraj,dwhswenson/mdtraj,jchodera/mdtraj,swails/mdtraj,mdtraj/mdtraj,tcmoore3/mdtraj,ctk3b/mdtraj,leeping/mdtraj,dwhswenson/mdtraj,mdtraj/mdtraj,ctk3b/mdtraj,msultan/mdtraj,dwhswenson/mdtraj,mpharrigan/mdtraj,tcmoore3/mdtraj,msultan/mdtraj,mattwthompson/mdtraj,mdtraj/mdtraj,rmcgibbo/mdtraj,tcmoore3/mdtraj,swails/mdtraj,swails/mdtraj,leeping/mdtraj,jchodera/mdtraj,gph82/mdtraj,leeping/mdtraj,rmcgibbo/mdtraj,mattwthompson/mdtraj,rmcgibbo/mdtraj,swails/mdtraj,msultan/mdtraj,gph82/mdtraj,ctk3b/mdtraj,mpharrigan/mdtraj,tcmoore3/mdtraj