Comment 1 for bug 214345

This is sort of deliberate. The Argentinian timezones are three-level - "America/Argentina/Buenos_Aires", etc. The installer only strips off one level of categorisation. My feeling at the moment is this results in them being categorised better and thus easier to find, even if it looks a bit odd.

Rather than just stripping all timezones down to a single level, perhaps it would be better to deal with this kind of thing by increased structure in the list display instead.