Description:
------------
When creating a DateTime from the WTC representation and then copying the DateTimeZone the comparison (<,>,==) fails.

In the example script PHP will say that 
2014-11-21 18:00:00 ==
2014-11-21 15:00:00
both with DateTimeZone -03:00, which is clearly wrong.

Test script:
---------------
$a = new DateTime("2014-11-21 15:00:00", new DateTimeZone("America/Santiago"));
echo "------------------\nCopying \$b from W3C representation of \$a\n";
$b = new DateTime($a->format(DateTime::W3C));
compare($a, $b);
$a->add(new DateInterval("PT3H"));
echo "------------------\nAdd 3 hours to \$a\n";
compare($a, $b);
$a->setTimezone($b->getTimezone());
echo "------------------\nSet Timezone of \$a to Timezone of \$b\n";
compare($a, $b);
echo "------------------\nCompare Timestamps:\n";
compare($a->getTimestamp(), $b->getTimestamp());

function compare($a, $b) {
    var_dump($a);
    var_dump($b);
    echo ($a > $b ? '$a > $b' : ($a < $b ? '$a < $b' : ($a == $b ? '$a == $b' : 'undefined'))) . "\n";
}

Expected result:
----------------
The time in the future should be greater than the time in the past, if the timezone is the same.

Actual result:
--------------
------------------
Copying $b from W3C representation of $a
class DateTime#1 (3) {
  public $date =>
  string(26) "2014-11-21 15:00:00.000000"
  public $timezone_type =>
  int(3)
  public $timezone =>
  string(16) "America/Santiago"
}
class DateTime#2 (3) {
  public $date =>
  string(26) "2014-11-21 15:00:00.000000"
  public $timezone_type =>
  int(1)
  public $timezone =>
  string(6) "-03:00"
}
$a == $b
------------------
Add 3 hours to $a
class DateTime#1 (3) {
  public $date =>
  string(26) "2014-11-21 18:00:00.000000"
  public $timezone_type =>
  int(3)
  public $timezone =>
  string(16) "America/Santiago"
}
class DateTime#2 (3) {
  public $date =>
  string(26) "2014-11-21 15:00:00.000000"
  public $timezone_type =>
  int(1)
  public $timezone =>
  string(6) "-03:00"
}
$a > $b
------------------
Set Timezone of $a to Timezone of $b
class DateTime#1 (3) {
  public $date =>
  string(26) "2014-11-21 18:00:00.000000"
  public $timezone_type =>
  int(1)
  public $timezone =>
  string(6) "-03:00"
}
class DateTime#2 (3) {
  public $date =>
  string(26) "2014-11-21 15:00:00.000000"
  public $timezone_type =>
  int(1)
  public $timezone =>
  string(6) "-03:00"
}
$a == $b
------------------
Compare Timestamps:
int(1416603600)
int(1416592800)
$a > $b