$ git clone -n https://src.fedoraproject.org/rpms/filesystem.git /var/lib/mock/f40-build-1996400-44010/root/chroot_tmpdir/scmroot/filesystem
Cloning into '/var/lib/mock/f40-build-1996400-44010/root/chroot_tmpdir/scmroot/filesystem'...
$ git fetch origin 02f4c34c92c42ddef004ba3bafb3aad4e0bebc3c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/filesystem
 * [new ref]         02f4c34c92c42ddef004ba3bafb3aad4e0bebc3c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 02f4c34 Add /etc/keys for initrd/kernel related keys