Comment 3 for bug 673637

No additional setup is required except setting EDITOR or BZR_EDITOR to point to emacsclient. Please note that the problem only happens on Windows (because the OS does not let bzr access the lock that is held by another instance of bzr). I never saw this on GNU/Linux.

You are right that Emacs does not need to be changed, I was just confused by the "Affects" link on the bug-reporting page.