$ git clone -n https://src.fedoraproject.org/rpms/blobwars.git /var/lib/mock/f40-build-1991792-43520/root/chroot_tmpdir/scmroot/blobwars
Cloning into '/var/lib/mock/f40-build-1991792-43520/root/chroot_tmpdir/scmroot/blobwars'...
$ git fetch origin 11e746aa0d9f6c8ecf29143b3e187e0beb7dc9d8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/blobwars
 * [new ref]         11e746aa0d9f6c8ecf29143b3e187e0beb7dc9d8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 11e746a Fix FTBFS (rhbz#2225725)