$ git clone -n https://src.fedoraproject.org/rpms/gtkmm4.0.git /var/lib/mock/f41-build-851483-165980/root/chroot_tmpdir/scmroot/gtkmm4.0
Cloning into '/var/lib/mock/f41-build-851483-165980/root/chroot_tmpdir/scmroot/gtkmm4.0'...
$ git fetch origin 074e0bfe2515ed21dc73deef4629b4fd4bd589f9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gtkmm4.0
 * [new ref]         074e0bfe2515ed21dc73deef4629b4fd4bd589f9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 074e0bf Update to 4.16.0