test_np_sum crash

[leezu]

[2020-05-27T04:27:37.644Z] tests/python/unittest/test_numpy_op.py::test_np_bool_agg[int8-True-True-True-shape9-all] 
[2020-05-27T04:27:37.644Z] [gw1] node down: Not properly terminated
[2020-05-27T04:27:37.644Z] [gw1] [ 26%] FAILED tests/python/unittest/test_numpy_op.py::test_np_sum[False-int32-int64-int64-True-0-shape0] 
[2020-05-27T04:27:37.644Z] 
[2020-05-27T04:27:37.644Z] replacing crashed worker gw1
[2020-05-27T04:27:37.900Z] 
[gw4] linux Python 3.6.9 cwd: /work/mxnet

http://jenkins.mxnet-ci.amazon-ml.com/blue/rest/organizations/jenkins/pipelines/mxnet-validation/pipelines/centos-cpu/branches/master/runs/1979/nodes/236/steps/284/log/?start=0

[yzhliu]

@JiangZhaoh will be helping.