$ git clone -n https://src.fedoraproject.org/rpms/ghc-cheapskate.git /var/lib/mock/f41-build-839713-160333/root/chroot_tmpdir/scmroot/ghc-cheapskate
Cloning into '/var/lib/mock/f41-build-839713-160333/root/chroot_tmpdir/scmroot/ghc-cheapskate'...
$ git fetch origin 491b7c6f4ec662c1360875dd300201100940642f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-cheapskate
 * [new ref]         491b7c6f4ec662c1360875dd300201100940642f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 491b7c6 patch for mtl 2.3