Which time zones make the list in ActiveSupport::TimeZone?

The documentation for ActiveSupport::TimeZone says one of the goals for the class is to “Limit the set of zones provided by TZInfo to a meaningful subset of 146 zones.”

Is there a canonical reference for these 146? It seems to me you’d want all the Time Zones defined by the TZInfo gem which in turn uses the IANA Time Zone database. I know you can include the tzinfo gem to get them all somehow but I’m just wondering how the list of 146 was derived (especially when other references say there are only 24 time zones around the world, which if you’re going for simplicity might have been another way to go).

I’m especially interested if N. Korea’s recent change to be a half hour off of Japan’s time zone (creating their own Time Zone) should be added to ActiveSupport::TimeZone. It has been added already to the IANA Time Zone database.