Multiphase integration test failed

[chicm-ms]

https://msrasrg.visualstudio.com/NNIOpenSource/_build/results?buildId=1630

I was not able to reproduce it on local system, but it occasionally failed on azure pipeline.

2019-01-22T03:09:30.1662354Z Traceback (most recent call last):
2019-01-22T03:09:30.1662620Z File "multi_phase.py", line 6, in
2019-01-22T03:09:30.1662677Z hyper_params = nni.get_next_parameter()
2019-01-22T03:09:30.1662783Z File "/home/nni/myagent/_work/1/s/src/sdk/pynni/nni/trial.py", line 44, in get_next_parameter
2019-01-22T03:09:30.1662837Z _params = platform.get_next_parameter()
2019-01-22T03:09:30.1662934Z File "/home/nni/myagent/_work/1/s/src/sdk/pynni/nni/platform/local.py", line 75, in get_next_parameter
2019-01-22T03:09:30.1662987Z params = json.load(params_file)
2019-01-22T03:09:30.1663036Z File "/usr/lib/python3.5/json/init.py", line 268, in load
2019-01-22T03:09:30.1663130Z parse_constant=parse_constant, object_pairs_hook=object_pairs_hook, **kw)
2019-01-22T03:09:30.1663185Z File "/usr/lib/python3.5/json/init.py", line 319, in loads
2019-01-22T03:09:30.1663276Z return _default_decoder.decode(s)
2019-01-22T03:09:30.1663324Z File "/usr/lib/python3.5/json/decoder.py", line 339, in decode
2019-01-22T03:09:30.1663677Z obj, end = self.raw_decode(s, idx=_w(s, 0).end())
2019-01-22T03:09:30.1663785Z File "/usr/lib/python3.5/json/decoder.py", line 357, in raw_decode
2019-01-22T03:09:30.1663838Z raise JSONDecodeError("Expecting value", s, err.value) from None
2019-01-22T03:09:30.1663929Z json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)
2019-01-22T03:09:30.4967110Z INFO: Stoping experiment tEtjD5xI
2019-01-22T03:09:30.4967347Z INFO: Stop experiment success!
2019-01-22T03:09:30.5346283Z Traceback (most recent call last):
2019-01-22T03:09:30.5346531Z File "config_test.py", line 99, in run
2019-01-22T03:09:30.5346929Z run_test(config_file, args.ts, args.local_gpu)
2019-01-22T03:09:30.5347904Z File "config_test.py", line 74, in run_test
2019-01-22T03:09:30.5348734Z assert num_succeeded == max_trial_num, 'only %d succeeded trial jobs, there should be %d' % (num_succeeded, max_trial_num)
2019-01-22T03:09:30.5349306Z AssertionError: only 1 succeeded trial jobs, there should be 2
2019-01-22T03:09:30.5349366Z