$ git clone -n https://src.fedoraproject.org/rpms/ghc-magic.git /var/lib/mock/f40-build-742252-110680/root/chroot_tmpdir/scmroot/ghc-magic
Cloning into '/var/lib/mock/f40-build-742252-110680/root/chroot_tmpdir/scmroot/ghc-magic'...
$ git fetch origin b207db76d298f61da45c49d9f5c1f05b359239c9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-magic
 * [new ref]         b207db76d298f61da45c49d9f5c1f05b359239c9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b207db7 bump release