facebook/hhvm — pull request #4459 by chizhengwang (2014-12-15 20:56:58+00:00)
Title: Change the iso format in ext_datetime.cpp

string(19) "1970-01-01 00:00:00"
["timezone_type"]=>
int(1)
["timezone"]=>
string(6) "+00:00"
}

instead of

object(DateTime)#1 (3) {
["date"]=>
string(19) "1970-01-01 00:00:00.000000"
["timezone_type"]=>
int(1)
["timezone"]=>
string(6) "+00:00"
}.