$ git clone -n https://src.fedoraproject.org/rpms/gtkmm4.0.git /var/lib/mock/f45-build-43639-804/root/chroot_tmpdir/scmroot/gtkmm4.0
Cloning into '/var/lib/mock/f45-build-43639-804/root/chroot_tmpdir/scmroot/gtkmm4.0'...
$ git fetch origin 9452983260f113fafa2d659bb1daec00f4750c8a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gtkmm4.0
 * [new ref]         9452983260f113fafa2d659bb1daec00f4750c8a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9452983 Update to 4.24.0