Create testchild.py
Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this [failed invocation](https://github.com/tensorflow/tensorflow/pull/60331/checks?check_run_id=12762224894) of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request. want to change in master branch Please don't spam
# Adding one line in child branch
print("Test child branch")