Fix a test to use an empty port to avoid flakiness
Fix a test to use an empty port to avoid flakiness

cjpatton/cloudproxy,jlmucb/cloudproxy,William-J-Earl/cloudproxy,jlmucb/cloudproxy,tmroeder/cloudproxy,jethrogb/cloudproxy,William-J-Earl/cloudproxy,jethrogb/cloudproxy,William-J-Earl/cloudproxy,kevinawalsh/cloudproxy,jethrogb/cloudproxy,cjpatton/cloudproxy,tmroeder/cloudproxy,cjpatton/cloudproxy,jlmucb/cloudproxy,jlmucb/cloudproxy,tmroeder/cloudproxy,cjpatton/cloudproxy,tmroeder/cloudproxy,kevinawalsh/cloudproxy,jethrogb/cloudproxy,William-J-Earl/cloudproxy,jlmucb/cloudproxy,tmroeder/cloudproxy,William-J-Earl/cloudproxy,jethrogb/cloudproxy,cjpatton/cloudproxy