statsmodels autopkgtest hangs

[Rebecca N. Palmer]

The statsmodels 0.11.1-2 autopkgtest timed out on Ubuntu arm64 and 
ppc64el, but succeeded in roughly the usual amount of time on Ubuntu 
amd64 and Debian arm64.

In both cases the last output was pytest's "collecting ... ", implying a 
hang at the test collection (not test running) stage, but not 
identifying which file it happened in.

Does it make sense to retry them?  (The self-service link for that 
requires a logon.)

If it's a real bug, I suspect the multiprocessing.Pool() in
https://salsa.debian.org/science-team/statsmodels/-/commit/04eeee8fed73330bced883720ff3b6eaedd89b11
but only compared to the (few) other changes from -1 to -2.