$ git clone -n https://src.fedoraproject.org/rpms/R-polynom.git /var/lib/mock/f40-build-1824137-24918/root/chroot_tmpdir/scmroot/R-polynom
Cloning into '/var/lib/mock/f40-build-1824137-24918/root/chroot_tmpdir/scmroot/R-polynom'...
$ git fetch origin 50996aaa8eacf6d61c3843cbbbf3fbe00212a91f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-polynom
 * [new ref]         50996aaa8eacf6d61c3843cbbbf3fbe00212a91f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 50996aa R-maint-sig mass rebuild