Pegasus MPI Cluster's Test PM848 fails on Debian 10 (Buster). The version of mpirun installed is different.

Example:

No. of processors = 8

SUCCESS: mpirun -np 8 echo 1
FAILURE: mpirun -np 9 echo 1

Fix:

Set -np to `nproc`. Will work on all platforms.

OR

Add --oversubscribe flag, this addition will have to be conditionally based on mpirun's version.

Select appropriate fix based on the purpose of the test case.