[tw-mbp-peiyu pants (master)]$ ./pants list testprojects/src/java/org/pantsbuild/testproject/shadingdep: --enable-v2-engine --config-override=pants.daemon.ini --no-verify-config
testprojects/src/java/org/pantsbuild/testproject/shadingdep:other
testprojects/src/java/org/pantsbuild/testproject/shadingdep:lib
testprojects/src/java/org/pantsbuild/testproject/shadingdep:shadingdep
Exception caught: (<type 'exceptions.AssertionError'>)
  File "/Users/peiyu/github/pants/src/python/pants/bin/daemon_pants_runner.py", line 158, in post_fork_child
    LocalPantsRunner(self._exiter, self._args, self._env, self._graph_helper).run()
  File "/Users/peiyu/github/pants/src/python/pants/bin/local_pants_runner.py", line 37, in run
    self._run()
  File "/Users/peiyu/github/pants/src/python/pants/bin/local_pants_runner.py", line 85, in _run
    run_tracker_result = run_tracker.end()
  File "/Users/peiyu/github/pants/src/python/pants/goal/run_tracker.py", line 337, in end
    self.shutdown_worker_pool()
  File "/Users/peiyu/github/pants/src/python/pants/goal/run_tracker.py", line 392, in shutdown_worker_pool
    SubprocPool.shutdown(self._aborted)
  File "/Users/peiyu/github/pants/src/python/pants/base/worker_pool.py", line 222, in shutdown
    old.join()
  File "/opt/twitter/Cellar/python/2.7.12_2/Frameworks/Python.framework/Versions/2.7/lib/python2.7/multiprocessing/pool.py", line 474, in join
    p.join()
  File "/opt/twitter/Cellar/python/2.7.12_2/Frameworks/Python.framework/Versions/2.7/lib/python2.7/multiprocessing/process.py", line 143, in join
    assert self._parent_pid == os.getpid(), 'can only join a child process'

Exception message: can only join a child process