$ git clone -n https://src.fedoraproject.org/rpms/xrootd.git /var/lib/mock/f39-build-1883406-42769/root/chroot_tmpdir/scmroot/xrootd
Cloning into '/var/lib/mock/f39-build-1883406-42769/root/chroot_tmpdir/scmroot/xrootd'...
$ git fetch origin 3aad3e6c6612b1ba722c458cee106854a5b0bd04:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xrootd
 * [new ref]         3aad3e6c6612b1ba722c458cee106854a5b0bd04 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3aad3e6 Enable erasure code support (XrdEc)