$ git clone -n https://src.fedoraproject.org/rpms/ghc-MemoTrie.git /var/lib/mock/f40-build-1998117-44209/root/chroot_tmpdir/scmroot/ghc-MemoTrie
Cloning into '/var/lib/mock/f40-build-1998117-44209/root/chroot_tmpdir/scmroot/ghc-MemoTrie'...
$ git fetch origin f780502a8749028b73ca7105e8d9bb4a08b0ded1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-MemoTrie
 * [new ref]         f780502a8749028b73ca7105e8d9bb4a08b0ded1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f780502 revise newtype-generics