Comment 5 for bug 504102

After some irc discussion we seem to agree that it's a bug that the RemoteBzrDirFormat contains a network_name that's implicitly mutated by calling methods on it. There is a general assumption that format objects are stateless/immutable. I'm not sure how hard that would be to remove.

Perhaps a bit hard because there are other methods on the Format that really are asking about the instance of the bzrdir.

For the moment I'm going to see if we can just avoid the side effect of setting the format network name.