$ git clone -n https://src.fedoraproject.org/rpms/ghc-cautious-file.git /var/lib/mock/f40-build-2074801-49439/root/chroot_tmpdir/scmroot/ghc-cautious-file
Cloning into '/var/lib/mock/f40-build-2074801-49439/root/chroot_tmpdir/scmroot/ghc-cautious-file'...
$ git fetch origin b2fd7f1288ae4f28219ad8fa7ed87403c37d6b3b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-cautious-file
 * [new ref]         b2fd7f1288ae4f28219ad8fa7ed87403c37d6b3b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b2fd7f1 bump release