pydata/pandas — pull request #1597 by changhiskhan (2012-07-10 16:44:17+00:00)
Title: Frame corr

kendalltau usually returns a tuple but for kendalltau([1, 1, 1], [1, 1, 1]) it returns int, so _kendall in nanops.get_corr_func was failing

if empty arrays are passed in, kendalltau leads to max recursion depth exceeded in mergesort, so must check valid.any before valid.all case.