Dear Maintainer, I observed the same issue on my system. Reinstalling libopenmpi-dev caused update-alternatives to figure out what was wrong and fixed the issue for me:
Setting up libopenmpi-dev:amd64 (4.0.2-2) ... update-alternatives: warning: forcing reinstallation of alternative /usr/lib/x86_64-linux-gnu/openmpi/include because link group mpi-x86_64-linux-gnu is broken The second time around, the /usr/lib/x86_64-linux-gnu/openmpi/lib/libmpi.so symlink exists and everything works. I'm not sure when exactly that is created, but like Ron, I suspect that it's too late. Cheers, Lorenz
