Attempt to fix Travis build errors.

Python 2 error is pytz dependency: https://travis-ci.org/tensorflow/datasets/builds/444720602

Python 3 error comes from NumPy. I added changes following your recommendation and they seem to work for Mesh TF: https://travis-ci.org/tensorflow/mesh/builds/444747095.

PiperOrigin-RevId: 218348018

Author: Dustin Tran

oss_scripts/oss_pip_install.sh

@@ -12,12 +12,13 @@ else
   pip install -q "tensorflow==$TF_VERSION"
 fi
 
+# Make sure we have the latest version of numpy - avoid problems we were
+# seeing with Python 3
+pip install -q -U numpy
+
 # First ensure that the base dependencies are sufficient for a full import
 pip install -q -e .
+python -c "import mesh_tensorflow as mtf"
 
 # Then install the test dependencies
 pip install -q -e .[tests]
-
-# Make sure we have the latest version of numpy - avoid problems we were
-# seeing with Python 3
-pip install -q -U numpy