$ git clone -n https://src.fedoraproject.org/rpms/jaxb-stax-ex.git /var/lib/mock/f42-build-3421928-45166/root/chroot_tmpdir/scmroot/jaxb-stax-ex
Cloning into '/var/lib/mock/f42-build-3421928-45166/root/chroot_tmpdir/scmroot/jaxb-stax-ex'...
$ git fetch origin 45907ff33ccdc72aacccd99b5fbe875644b8562c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/jaxb-stax-ex
 * [new ref]         45907ff33ccdc72aacccd99b5fbe875644b8562c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 45907ff Remove javadoc subpackage