$ git clone -n https://src.fedoraproject.org/rpms/ghc-system-filepath.git /var/lib/mock/f41-build-837792-159384/root/chroot_tmpdir/scmroot/ghc-system-filepath
Cloning into '/var/lib/mock/f41-build-837792-159384/root/chroot_tmpdir/scmroot/ghc-system-filepath'...
$ git fetch origin fabc346784b1cb48b0579bac25bf33aa536331d7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-system-filepath
 * [new ref]         fabc346784b1cb48b0579bac25bf33aa536331d7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at fabc346 refresh .cabal revision