Code review comment for lp:~edwin-grubbs/launchpad/bug-576388-proposing-invited-team

1. 'Accepted invitation whilst trying to propose the team' is awkward. Rephrase to something like "Accepted an already pending invitation while trying to propose the team for membership."

2. The "Accepted an already pending invitation" string isn't tested. Would it be difficult to show where that string is used (I'm guessing in an email)? If it's very difficult to test, I think it's not a big deal.

r=me with those changes.