$ git clone -n https://src.fedoraproject.org/rpms/gucharmap.git /var/lib/mock/f39-build-1492431-34529/root/chroot_tmpdir/scmroot/gucharmap
Cloning into '/var/lib/mock/f39-build-1492431-34529/root/chroot_tmpdir/scmroot/gucharmap'...
$ git fetch origin 939f574866c619c6f5a90a4e08f50215e2af5920:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gucharmap
 * [new ref]         939f574866c619c6f5a90a4e08f50215e2af5920 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 939f574 Update to 15.1.2