PROTON-693: If the system doesn't have port definitions for amqp/amqps use the default values of 5672/5671. - Not all systems have /etc/service (or similar) files that define these ports, but our tests use them and the defaults are these strings.
qpid/proton/trunk/proton-c/bindings/python/proton.py
qpid/proton/trunk/tests/python/proton_tests/url.py