$ git clone -n https://src.fedoraproject.org/rpms/R-RUnit.git /var/lib/mock/f43-build-side-110352-58908756-6569187/root/chroot_tmpdir/scmroot/R-RUnit
Cloning into '/var/lib/mock/f43-build-side-110352-58908756-6569187/root/chroot_tmpdir/scmroot/R-RUnit'...
$ git fetch origin 62b90394a16b58b1b2f69b43b282410744a51c8e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-RUnit
 * [new ref]         62b90394a16b58b1b2f69b43b282410744a51c8e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 62b9039 R-maint-sig mass rebuild