$ git clone -n https://src.fedoraproject.org/rpms/greyhounds.git /var/lib/mock/f41-build-778271-13541/root/chroot_tmpdir/scmroot/greyhounds
Cloning into '/var/lib/mock/f41-build-778271-13541/root/chroot_tmpdir/scmroot/greyhounds'...
$ git fetch origin d074e4dd724993dd1b81a02166d7590cc284406e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/greyhounds
 * [new ref]         d074e4dd724993dd1b81a02166d7590cc284406e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d074e4d Eliminate use of obsolete %patchN syntax (#2283636)