Python tests do not pass on 1.x branch if it has not been released

Apr 19 11:39:38   Downloading https://files.pythonhosted.org/packages/6c/38/ff06cec1b32e796c8422153d6d29a6c8c6dab962436779e34b0d72df0f2f/grpcio-tools-1.14.2.tar.gz (1.9MB)
Apr 19 11:39:38 Collecting apache-flink-libraries
Apr 19 11:39:38   Downloading https://files.pythonhosted.org/packages/6c/b1/78dcaec55a437c3b8b3eb479b169d7fac15e86ffe9bd7340767934ceab2f/apache_flink_libraries-0.0.tar.gz (3.5MB)
Apr 19 11:39:38     Complete output from command python setup.py egg_info:
Apr 19 11:39:38     The flink core files are not found. Please make sure your installation package is complete, or do this in the flink-python directory of the flink source directory.