Livy python-api client test failing

When building Livy master, the livy-python-api module client_test fails with the following:
__________ ERROR collecting src/test/python/livy-tests/client_test.py __________
src/test/python/livy-tests/client_test.py:29: in <module>
base_uri = 'http://{}:{}'.format(socket.gethostname(), 8998)
E ValueError: zero length field name in format

Prior to python 2.7 the field number needs to be specified.