Comment 11 for bug 207604

I'll take a look at the lazier init patch now we no longer support Python 2.3 - writing a lazy set seemed impossible before for Python 2.3 - Python 2.6.

Another approach - since we are distributing the compiled zoneinfo database, we can add an extra datafile containing the information we currently generate at run time - the list of all installed timezones, information parsed from zone.tab. If the resource exists, use and trust it. If it does not, fall back to the existing methods (we need the fall back to support installations that make use of the system's compiled zoneinfo database).