The binNMUs (to add python3.8 support) of pandas and statsmodels failed.
I think this will make them work (but haven't tried it):
- Apply the (existing) #943418 fix to python-xlrd.
- Build matplotlib, pandas and statsmodels in that order. (ben can't
work this out because the declared dependencies are circular, but I
think the actual strict test dependencies only go that way.)