need to have DMLC_JOB_CLUSTER?

[PayneJoe]

example: ./tracker/dmlc-submit --jobname fm_feed --cluster yarn ... cluster variable already specified ,why this error still happens in tracker.py ?

assert cluster is not None, 'need to have DMLC_JOB_CLUSTER' AssertionError: need to have DMLC_JOB_CLUSTER

By the way, I use the python2