Converting a negative date with DateTime get me false
Test code
var_dump(\DateTime::createFromFormat(\DateTime::ISO8601, '-0001-11-30T00:00:00+0100'));
Result
boolean false
Expected result
object(DateTime)[5] public 'date' => string '-0001-11-30 00:00:00' (length=20) public 'timezone_type' => int 1 public 'timezone' => string '+01:00' (length=6)
(or something similar)
P.S. The negative date string was created with $d->format(\DateTime::ISO8601);
PHP version PHP 5.4.28