astropy/astropy — pull request #1599 by taldcroft (2013-10-18 02:21:52+00:00)
Title: Use mergesort in groups sorting to maintain original order

Running table tests failed on mac because the quicksort alg gives a different order than on linux. There is no guarantee that quicksort is stable, so this PR switches the sort algorithm to mergesort, which *is* stable.