$ git clone -n https://src.fedoraproject.org/rpms/ghc-tar.git /var/lib/mock/f45-build-10817-424/root/chroot_tmpdir/scmroot/ghc-tar
Cloning into '/var/lib/mock/f45-build-10817-424/root/chroot_tmpdir/scmroot/ghc-tar'...
$ git fetch origin ab102f7adda6764ad61482b8174b9bf6cfcbd05a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-tar
 * [new ref]         ab102f7adda6764ad61482b8174b9bf6cfcbd05a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ab102f7 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild