pydata/pandas — pull request #4461 by waitingkuo (2013-08-05 09:23:07+00:00)
Title: Fix issue 4160

## Fix Issue #4160

While renamed a `MultiIndex`, the `mapper` walk through every tuple in the MultiIndex and every element in a tuple. So the mapper { (index1, index2): (new_index1, new_index2) } didn't work for the MultiIndex case.

This pull request is to modify it to walk through every tuple in a MultiIndex and use the mapper to map each tuple.
Also, the test case has been added.