$ git clone -n https://src.fedoraproject.org/rpms/R-RPostgres.git /var/lib/mock/f40-build-1944392-25177/root/chroot_tmpdir/scmroot/R-RPostgres
Cloning into '/var/lib/mock/f40-build-1944392-25177/root/chroot_tmpdir/scmroot/R-RPostgres'...
$ git fetch origin 961427d855dbf58fd7de2b7f59a2fa788b1b419a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-RPostgres
 * [new ref]         961427d855dbf58fd7de2b7f59a2fa788b1b419a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 961427d R-maint-sig mass rebuild