This issue came about because the polar axes which had already been created via plt.subplot wasn't getting picked up with a simple plt.gca(projection='polar') due to different gridspecs. I have removed the use of the gridspec in the key comparison of gca, and added a few tests which cover these changes.
Fixed transoffset example from failing.
This part wasn't necessary, but is out of date and redundant. I would be willing to put it back in if requested.