When we enabled fxcop with a superset of the "Microsoft All Rules" ruleset for one of our projects it also enabled CA1309 and immediately started complaining about constructions such as this:
if (translationItem.Description == "Description")
if (string.Equals(translationItem.Description, "Description", StringComparison.Ordinal))
Not much of an answer but, per request of cynic from the comments, an issue has been raised over at the roslyn github. As soon as the issue has been resolved, this answer will be updated. For now, we wait.