[MTT users] MPI details: after_each_exec lesson learned

[Jeff Squyres]

We learned a pretty hard lesson about the after_each_exec step in the  
MPI Details section over the past few weeks, particularly when used  
in conjunction with SLURM's "srun" command (although this is not a  
SLURM-specific issue).

I highly encourage everyone to read the commit message for r657 -- it  
changed what we do at Cisco in the after_each_exec step:

    https://svn.open-mpi.org/trac/mtt/changeset/657

--
Jeff Squyres
Cisco Systems