TST: grouped_hist not closing properly on 3.4/windows
Starting with the 2nd commit the following test:

`tests/test_groupby/test_series_groupby_plotting_nomially_works`
started failing (works on the first, fails on the 2nd)

on 3.4/windows

https://github.com/pydata/pandas/commit/cd422c2f256ef5bd2a8315e1c177c9e1d8947d4a

https://github.com/pydata/pandas/commit/4c30610f1b6494c48699621755961e98c8fc7805

Its killing python on the 2nd `tm.close()`
I stepped thru it and the first fignum is ok, but there are 2 and the 2nd one crashes it

what changed?

running matplotlib 1.3.1
