[tz] Moving more zones to 'backzone'

[Clive D.W. Feather]

Eliot Lear via tz said:
> > I'm not sure if the above is an appropriate characterization, but I want
> > to point out that switching much of Europe to Europe/Berlin will leaves
> > us ill-equipped to deal with future time zone fragmentation after
> > mandatory DST has been abolished in Europe, and different countries make
> > different choices.
> 
> Let's be specific.  I think the example in question is  if Berlin and 
> Stockholm diverge due to one wanting DST and the other not. At that 
> point, what happens to Stockholm?  Does it get a new or does it point to 
> another city?

The area covered by Europe/Berlin will split into two time zones (in the TZ
sense). We identify the largest city in each (one of which will presumably
be Berlin) and ensure we have zones for each, either by creating new ones
or reinstating ones that have been moved to backzone.

If Sweden is the only country to take the opposite view to Germany, then the
zones will be Europe/Berlin and Europe/Stockholm. At which point I'd expect
us to re-instate all the data that got lost when the merge happened.

If other countries disagree with Germany, Stockholm might not be the
largest city (I can't be bothered to look up what the merges were) but the
principle still applies.

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Clive D.W. Feather          | If you lie to the compiler,
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