Thread: pgsql: timestamptz_trunc() should only recalculate the timezone when

Log Message:
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timestamptz_trunc() should only recalculate the timezone when truncating
to DAY precision or coarser; leave the timezone alone when precision is
HOUR or less.  This avoids surprises for inputs near a DST transition
time, as per example from Matthew Gabeler-Lee.  (The only reason we
recalculate at all is so that outputs that are supposed to represent
days will come out as local midnight, and that's not relevant for sub-day
precision.)

Modified Files:
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    pgsql/src/backend/utils/adt:
        timestamp.c (r1.113 -> r1.114)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/timestamp.c.diff?r1=1.113&r2=1.114)