Wow, that was fast! The Open MPI 4.0.2-3 updates appear to resolve the issue. I say "appear" because I can't really reproduce an upgrade from 3.1.3 to 4.0.2-3.
Upgrading from 4.0.2-2 to 4.0.2-3 worked fine. In order to test a new installation of Open MPI, I removed all Open MPI and OpenCoarrays packages, then installed mpi-default-bin and mpi-default-dev to bring them back. I used apt-get for that in case I needed to capture some messages. There were no issues reported, and 4.0.2-3 works fine on my test programs, including Co-Array Fortran tests. I also noticed that libopenmpi-dev now depends on libevent-dev as I suggested in Bug #945121. Great work, guys! -- James Ronald Lovell <ron163...@gmail.com> Huntsville, AL, USA