wesm/pandas — pull request #665 by ogrisel (2012-01-22 13:39:45+00:00)
Title: BUG: resolve lef/right key names overlap in merge

Here is an attempt at fully resolving name conflict in merges when `left_on` or `right_on` keys are passed explicitly.

I am not sure my fix is correct but I include a new non-regression test to highlight the issue and the resolution does not introduce any regression findable by running `nosetests`.