/usr/share/doc/mpich-shmem-bin/changelog.Debian.gz is in mpich-shmem-bin 1.2.7-10ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/mpich-shmem-bin/../libmpich-shmem1.0gf/changelog.Debian.gz