$ git clone -n https://src.fedoraproject.org/rpms/libguestfs.git /var/lib/mock/f40-build-1177402-21835/root/chroot_tmpdir/scmroot/libguestfs
Cloning into '/var/lib/mock/f40-build-1177402-21835/root/chroot_tmpdir/scmroot/libguestfs'...
$ git fetch origin b68f2bb6d10071c2160b766cd421c64abbf69f86:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libguestfs
 * [new ref]         b68f2bb6d10071c2160b766cd421c64abbf69f86 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b68f2bb New stable branch version 1.52.1