/usr/share/man/man1/mpiexec.hydra.1.gz is in mpich 3.1-5+b2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man1/mpiexec.mpich.1.gz
/usr/share/man/man1/mpiexec.mpich.1.gz