TST: remove rest of yield warnings
xref https://github.com/pandas-dev/pandas/issues/15341
Great! yeah these were annoying mainly on the https://travis-ci.org/MacPython/pandas-wheels/builds

trying to get these to daily build (almost there, *most* build but uploading not working yet).
(though 32-bit still failing some).

 you couldn't scroll down easily :<