$ git clone -n https://src.fedoraproject.org/rpms/xrootd.git /var/lib/mock/f40-build-805343-144757/root/chroot_tmpdir/scmroot/xrootd
Cloning into '/var/lib/mock/f40-build-805343-144757/root/chroot_tmpdir/scmroot/xrootd'...
$ git fetch origin 0a46bf1aee0b0cfbaca5ff8a5239cf5e3ad7594d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xrootd
 * [new ref]         0a46bf1aee0b0cfbaca5ff8a5239cf5e3ad7594d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0a46bf1 Update sources