fixed python test error (#387)
fixed python test error (#387)

cla: yes
* fixed python test error

* revert some of earlier changes, and pin the estimator to the same date as tf

tensorflow/tfjs,tensorflow/tfjs,tensorflow/tfjs-converter,tensorflow/tfjs-converter,tensorflow/tfjs,tensorflow/tfjs,tensorflow/tfjs-converter,tensorflow/tfjs-converter,tensorflow/tfjs,tensorflow/tfjs-converter,tensorflow/tfjs,tensorflow/tfjs,tensorflow/tfjs,tensorflow/tfjs