$ git clone -n https://src.fedoraproject.org/rpms/libxmlb.git /var/lib/mock/f40-build-2220022-52649/root/chroot_tmpdir/scmroot/libxmlb
Cloning into '/var/lib/mock/f40-build-2220022-52649/root/chroot_tmpdir/scmroot/libxmlb'...
$ git fetch origin f800a69c5504858f5c0bcdcb6e274624f6fb79cb:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libxmlb
 * [new ref]         f800a69c5504858f5c0bcdcb6e274624f6fb79cb -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f800a69 New upstream release