Failed test with latest PHP versions

[remicollet]

Discovered in Fedora QA: https://apps.fedoraproject.org/koschei/package/php-justinrainbow-json-schema?collection=f25

Since update from 7.0.9RC1 to 7.0.9 (which should not break anything, as only security fix)

1) JsonSchema\Tests\Constraints\FormatTest::testInvalidFormat with data set #10 ('-1', 'utc-millisec')
Expected 1 error
Failed asserting that 0 matches expected 1.

/dev/shm/BUILD/json-schema-6b2a33e6a768f96bdc2ead5600af0822eed17d67/tests/Constraints/FormatTest.php:66

Also fails with PHP 5.6.24
V1 also fails (same error)

[remicollet]

Additional info:

$ php54 -r 'var_dump(DateTime::createFromFormat("U", -1));'
bool(false)

$ php55 -r 'var_dump(DateTime::createFromFormat("U", -1));'
bool(false)

$ php56 -r 'var_dump(DateTime::createFromFormat("U", -1));'
object(DateTime)#1 (3) {
  ["date"]=>
  string(26) "1969-12-31 23:59:59.000000"
  ["timezone_type"]=>
  int(1)
  ["timezone"]=>
  string(6) "+00:00"
}

$ php70 -r 'var_dump(DateTime::createFromFormat("U", -1));'
object(DateTime)#1 (3) {
  ["date"]=>
  string(26) "1969-12-31 23:59:59.000000"
  ["timezone_type"]=>
  int(1)
  ["timezone"]=>
  string(6) "+00:00"
}

$ php71 -r 'var_dump(DateTime::createFromFormat("U", -1));'
object(DateTime)#1 (3) {
  ["date"]=>
  string(26) "1969-12-31 23:59:59.000000"
  ["timezone_type"]=>
  int(1)
  ["timezone"]=>
  string(6) "+00:00"
}

[derickr]

This is a bug fix, where "U" now also understand negative timestamps. -1 gets converted to "-1".