Fix error in exit status when running python tests (#1631)
Fix error in exit status when running python tests (#1631)

* Correct command exit status
intel-analytics/BigDL,yangw1234/BigDL,yangw1234/BigDL,yangw1234/BigDL,intel-analytics/BigDL,yangw1234/BigDL,intel-analytics/BigDL,intel-analytics/BigDL