On my normal environment, OSX 10.12.6 on a Macbook Pro Retina, I am
getting multiple image test failures that are *not* just the usual
freetype problems. (I am using 'export MPLLOCALFREETYPE=1' in my
.bashrc.) The failures are most visible in the diffs of the spectrum plots.
Is anyone else seeing this, or are others on OSX able to get all of the
tests to pass?