message: turns out we can enable this sanity check now
diff: @@ -547,9 +547,7 @@ impl<'a, 'tcx, M: Machine<'tcx>> Memory<'a, 'tcx, M> {
  None => {
  // Make sure we did not try to release someone else's lock.
  if !is_our_lock && lock.active != NoLock {
  - // FIXME: For the same reason that we have to live with suspensions already existing,
  - // we also cannot be sure here if things really are going wrong. So accept this for now.
  - //return err!(InvalidMemoryLockRelease { ptr, len, frame: cur_frame, lock: lock.active.clone() });
  + return err!(InvalidMemoryLockRelease { ptr, len, frame: cur_frame, lock: lock.active.clone() });
  }
  }
  }
  