Comment 1 for bug 664376

Which OS/bzr version are you using ?

Almost all our tests use '0' to ask the system to assign a free port number. It's pretty weird that you get such an error here.

Do you use IPV6 ? (I can't remember if you can easily disable it on OSX).
The bug is propably pretty shallow but needs to be either diagnosed on your host or reproduced somewhere else.

Also, a traceback will help.