Failures in node.test with assertFieldByXPath

Noticed on slave #4 (using PHP 5.2.0) we had a failure in each the node preview and node edit tests. I couldn't duplicate the failures on my install with PHP 5.2.4. The line of failure was:
$this->assertFieldByName('body', '<!--break-->' . $edit['body'], t('Body field displayed.'));
and
$this->assertFieldByName('body', '<!--break-->' . $edit['body'], t('Body field displayed.'));

Did lots of debugging ito assertFieldByXPath (used by assertFieldByName), and discovered this logic for textareas:

          elseif (isset($field[0]) && $field[0] == $value) {
             // Text area with correct text.
             $found = TRUE;
           }

My inclination is that on the older version of PHP using $field[0] is returning the first character of the textarea, so trying to compare it to $value fails. Patch changes the logic to:

          elseif ((string) $field == $value) {
             // Text area with correct text.
             $found = TRUE;
           }

Boombatower confirmed that this fixes the failures on slave #4. Tests still pass for me on my local. This is critical as it is the only blocker from getting testing bot running again.