Bug#993214: mpi4py: autopkgtest regression around 2021-08-25

[Graham Inggs]

Hi Drew

I followed the discussion on the upstream issue.
What do you think of adding some extra test dependencies to mpi4py's
debian/tests/control?

 Depends: python3-mpi4py,
+    libpmix-dev,
+    libucx-dev [amd64 arm64 ppc64el],
     python3-cffi,
     python3-dill,
     python3-distutils,

This will make sure mpi4py's autopkgtests are run when pmix and ucx
are updated as well.

Regards
Graham