[tz] Converting cities to tz identifiers (tangent)

[Paul Eggert]

John Hawkinson wrote:
> The "US Eastern time zone" is coterminus with the America/New_York boundary (I think).

Not really: even inside the US, the US Eastern time zone currently also includes 
America/Indiana/Indianapolis, America/Indiana/Marengo, 
America/Indiana/Vincennes, America/Indiana/Petersburg, America/Indiana/Winamac, 
America/Indiana/Vevay, America/Kentucky/Louisville, America/Kentucky/Monticello, 
and America/Detroit. And several locations outside the US are currently in the 
same time zone, e.g., America/Nassau.