BUG: Error in rolling_var if window is larger than array, fixes #7297
Merge pull request #7572 from jaimefrio/rolling_var_bug

BUG: Error in rolling_var if window is larger than array, fixes #7297
TST: fixes for 2.6 comparisons
Revert "Merge pull request #7591 from mcwitt/parse-index-cols-c"

This reverts commit 2c603e17b60665b5db6b373f33e1479f47b7155a, reversing
changes made to 49a86f1fb90ea199cba0954ede6b939f672867b1.