$ git clone -n https://src.fedoraproject.org/rpms/R-lobstr.git /var/lib/mock/f38-build-724025-99309/root/chroot_tmpdir/scmroot/R-lobstr
Cloning into '/var/lib/mock/f38-build-724025-99309/root/chroot_tmpdir/scmroot/R-lobstr'...
$ git fetch origin a862f47fdbb1a56fd36f8015f0744a346bc58ea3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-lobstr
 * [new ref]         a862f47fdbb1a56fd36f8015f0744a346bc58ea3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a862f47 R-maint-sig mass rebuild