$ git clone -n https://src.fedoraproject.org/rpms/R-rematch.git /var/lib/mock/f45-build-6343-348/root/chroot_tmpdir/scmroot/R-rematch
Cloning into '/var/lib/mock/f45-build-6343-348/root/chroot_tmpdir/scmroot/R-rematch'...
$ git fetch origin 6d98e487e8c52e7e22fb3e084e7178e9dd583f6c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-rematch
 * [new ref]         6d98e487e8c52e7e22fb3e084e7178e9dd583f6c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6d98e48 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild