error message should print out stack info instead of object

[kaelzhang]

dist dir "/root/.cortex/default/modules/neuron/7.1.0/package/dist" found, �[36mskip�[0m building ...
 �[36mcopy�[0m /root/.cortex/default/modules/neuron/7.1.0/package/dist -> /root/.jenkins/workspace/alpha-jiayi.xu-unit-m-customer-test-alpha/neurons/neuron/7.1.0
�[1m�[31mERR!�[0m [ { [Error: EEXIST, mkdir '/root/.jenkins/workspace/alpha-jiayi.xu-unit-m-customer-test-alpha/neurons/neuron/7.1.0']
    errno: 47,
    code: 'EEXIST',
    path: '/root/.jenkins/workspace/alpha-jiayi.xu-unit-m-customer-test-alpha/neurons/neuron/7.1.0' } ]