Description:
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DateTime::createFromFormat not checking properly provided format (day [01-31] and month [01-12] limitations) and only checking number of digits. 

Test script:
---------------
<?php
var_dump(DateTime::createFromFormat('Y-m-d', '9999-99-99'));

Expected result:
----------------
bool(false)

Actual result:
--------------
object(DateTime)#9 (3) {
  ["date"]=>
  string(20) "10007-06-07 13:28:21"
  ["timezone_type"]=>
  int(3)
  ["timezone"]=>
  string(13) "Europe/Berlin"
}