Thanks again. So localtime()->strptime does behave differently.

So localtime()->strptime's handling of time zones is the underlying issue. Certainly these two should be equivalent, no?

#!/usr/bin/env perl

use strict;
use warnings;

use Test::More ('no_plan');
use Time::Piece;

$ENV{'TZ'} = 'America/Los_Angeles';

my @tests = (
  ['2017-06-19 10:07:42', '%Y-%m-%d %H:%M:%S'],
  ['2017-06-19 10:07:42-0700', '%Y-%m-%d %H:%M:%S%z'],
);

is($Time::Piece::VERSION, 1.31);

foreach my $test (@tests) {
  my ($datestr, $fmt) = @$test;
  my $t = localtime->strptime($datestr, $fmt);

  is($t->epoch, 1497892062);
  is($t->tzoffset, -25200);
  is($t->strftime, 'Mon, 19 Jun 2017 10:07:42 PDT');
  is($t->strftime('%Y-%m-%d %H:%M:%S'), $datestr);
}
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Result

ok 1
ok 2
ok 3
ok 4
ok 5
not ok 6
#   Failed test at ./try7 line 22.
#          got: '1497917262'
#     expected: '1497892062'
ok 7
not ok 8
#   Failed test at ./try7 line 24.
#          got: 'Mon, 19 Jun 2017 17:07:42 PDT'
#     expected: 'Mon, 19 Jun 2017 10:07:42 PDT'
not ok 9
#   Failed test at ./try7 line 25.
#          got: '2017-06-19 17:07:42'
#     expected: '2017-06-19 10:07:42-0700'
1..9
# Looks like you failed 3 tests of 9.
[download]