It turns out a bug fix PR (#1265) broke my own feature PR (#1090) of having an external _as_mpl_transform api.
Even if this doesn't make it in the final 1.2 cut (i.e. we don't find any issues with RC2), I think it is worth merging into the 1.2 branch.
Because we are so close to a release, I have tried to minimize any changes, hence have not changed the ContourSet's transform attribute to be private (i.e. _transform).
Fixed to contour to support the _as_mpl_transform api.
I would vote to fix the self.transform to self._transform now before release. Once we release it that way, we are largely stuck with it. The choice of API is very important and not to be taken lightly.
Updated ContourSet api to make transform private (in favour of using …
…a get_transform method).
Have done. Thanks @WeatherGod.