Code review comment for lp:~cablespaghetti/gwibber/retweetbugfix

The changes fix this bug:
https://bugs.launchpad.net/gwibber/+bug/404939

However I only have a twitter account and so can only guarantee that the changes work with twitter. That said, I haven't changed anything that should affect other services.

I hope I've done this right as I have no prior experience with bzr or launchpad.