pydata/pandas — pull request #8541 by TomAugspurger (2014-10-11 19:51:12+00:00)
Title: BUG: Plot with ``label`` would overwrite index name

Closes https://github.com/pydata/pandas/issues/8494

I took the easy solution and just copied the series.

Alternatively we could attach a label property to the MPLObject, and check that wherever we check the index name.