$ git clone -n https://src.fedoraproject.org/rpms/ghc-feed.git /var/lib/mock/f41-build-840171-160595/root/chroot_tmpdir/scmroot/ghc-feed
Cloning into '/var/lib/mock/f41-build-840171-160595/root/chroot_tmpdir/scmroot/ghc-feed'...
$ git fetch origin b9da9bc26db5453f1cff042ee9e55511e25381a7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-feed
 * [new ref]         b9da9bc26db5453f1cff042ee9e55511e25381a7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b9da9bc refresh .cabal revision