$ git clone -n https://src.fedoraproject.org/rpms/glib2.git /var/lib/mock/f42-build-side-1-3588867-46950/root/chroot_tmpdir/scmroot/glib2
Cloning into '/var/lib/mock/f42-build-side-1-3588867-46950/root/chroot_tmpdir/scmroot/glib2'...
$ git fetch origin 81d2ab42469a505b4ef8d99e12d308daed812e71:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/glib2
 * [new ref]         81d2ab42469a505b4ef8d99e12d308daed812e71 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 81d2ab4 Update to 2.84.3