$ git clone -n https://src.fedoraproject.org/rpms/R-rcmdcheck.git /var/lib/mock/f40-build-2114782-50675/root/chroot_tmpdir/scmroot/R-rcmdcheck
Cloning into '/var/lib/mock/f40-build-2114782-50675/root/chroot_tmpdir/scmroot/R-rcmdcheck'...
$ git fetch origin 57d5ab8f5ff2215a34b94fe2b1962bf86ac3a17e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-rcmdcheck
 * [new ref]         57d5ab8f5ff2215a34b94fe2b1962bf86ac3a17e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 57d5ab8 Convert to %autorelease and %autochangelog