$ git clone -n https://src.fedoraproject.org/rpms/jaxb.git /var/lib/mock/f38-build-side-42-init-devel-645185-26400/root/chroot_tmpdir/scmroot/jaxb
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-645185-26400/root/chroot_tmpdir/scmroot/jaxb'...
$ git fetch origin e750d03c58dcacc9bed143331a013e02c67de3ba:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/jaxb
 * [new ref]         e750d03c58dcacc9bed143331a013e02c67de3ba -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e750d03 Update to upstream version 4.0.2