Decide if it's safe to unzip the new TBB into the old TBB directory
Some of our users upgrade their TBB in-place, by unzipping the new one over the old one. The benefit is that they get to keep their bookmarks, extensions, etc.
Are there drawbacks that are going to bite them eventually, e.g. when we change something in TBB and users get different behavior depending on whether they have a fresh unzip or they overwrite an old unzip?
It seems we've been recommending this behavior to users, so we should decide whether to continue or stop.