/usr/bin/tstmachines.mpich-mpd is in mpich-mpd-bin 1.2.7-10ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/bin/../lib/mpich-mpd/sbin/tstmachines
/usr/bin/../lib/mpich-mpd/sbin/tstmachines