[tz] Indian Time zone history and choice of Kolkata as reference location

[Paul Eggert]

Alois Treindl wrote:

> TZ was conscious of that problem

By "TZ" I guess you mean me, since I contributed the Indian data. If my guess is 
correct, then this statement is mistaken. When I made that contribution decades 
ago, I was not aware of the problems of historical time in India. Also, Calcutta 
was listed as the largest city in India in the source I casually consulted 
(sorry, I don't remember what it was). Although Delhi is the largest city in 
India now, it's not clear that it would be worth the technical and political 
hassle to switch names at this point, just as it's not clear that it would be 
worth switching Europe/Rome to Europe/Milan.

If this situation comes up again when adding future entries, the theory.html 
file does not currently suggest preferring locations whose pre-1970 timestamp 
history is more reliable. I'm not sure we should add anything like that, but if 
we do the suggestion would be low priority because pre-1970 timestamps are lower 
priority.