$ git clone -n https://src.fedoraproject.org/rpms/python-slixmpp.git /var/lib/mock/f39-build-1488142-34496/root/chroot_tmpdir/scmroot/python-slixmpp
Cloning into '/var/lib/mock/f39-build-1488142-34496/root/chroot_tmpdir/scmroot/python-slixmpp'...
$ git fetch origin dd31219aa71b0f6e83a0f7942f1eadfd18f76cc6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/python-slixmpp
 * [new ref]         dd31219aa71b0f6e83a0f7942f1eadfd18f76cc6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at dd31219 Update to 1.8.4