$ git clone -n https://src.fedoraproject.org/rpms/xrootd.git /var/lib/mock/f39-build-2262361-54438/root/chroot_tmpdir/scmroot/xrootd
Cloning into '/var/lib/mock/f39-build-2262361-54438/root/chroot_tmpdir/scmroot/xrootd'...
$ git fetch origin 07036ad772ccf9a4473482215c73dc533c2a0047:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xrootd
 * [new ref]         07036ad772ccf9a4473482215c73dc533c2a0047 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 07036ad Update to version 5.6.4