$ git clone -n https://src.fedoraproject.org/rpms/R-lobstr.git /var/lib/mock/f40-build-1944513-25177/root/chroot_tmpdir/scmroot/R-lobstr
Cloning into '/var/lib/mock/f40-build-1944513-25177/root/chroot_tmpdir/scmroot/R-lobstr'...
$ git fetch origin 6efe08d3499ab99002319230fa7f842a7948c3ec:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-lobstr
 * [new ref]         6efe08d3499ab99002319230fa7f842a7948c3ec -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6efe08d R-maint-sig mass rebuild