bug#7337: 23.2; (require 'time) changes timezone

[Chong Yidong]

Kevin Ryde <user42@zip.com.au> writes:

> Oh, they might be dodgy too.  I suppose set-time-zone-rule changes the C
> level environ[], but the lisp `getenv' looks in the process-environment
> variable, not environ[].  Does that sound right?  Should
> set-time-zone-rule set TZ in process-environment?

Yes, Lisp code should typically use (setenv "TZ" ...) rather than
set-time-zone-rule for this reason.  I have updated the doc of
set-time-zone-rule, and changed the users of set-time-zone-rule
accordingly.