Log when git gc runs.  It can be slow.

The full Date-Manip import too 17 minutes on my laptop vs 1 minute for
the push.  Without logging the gc it looks like all the time was in
the push.
Run git gc before pushing.  Faster overall.

The push can be significantly slower on a non-gc'd repository.  It still
pushes the same amount, but it can take quite some time to read the
un-garbage collected repository.  Date-Manip took over a minute to push
without a gc but only 14 seconds after.  Both pushed about 7 megs.
Test that temp files are cleaned up when a Release is destroyed.