im getting an error on install - Warning: Illegal string offset 'field' in DatabaseCondition->__clone() (line 1901 .........

Hello.

i have installed 7.12 because im dupliacting a drupal site but im getting this error:

Warning: Illegal string offset 'field' in DatabaseCondition->__clone() (line 1901 of /Applications/MAMP/htdocs/drupal/includes/database/query.inc).

this is the code

 function __clone() {
    $this->changed = TRUE;
    foreach ($this->conditions as $key => $condition) {
    if ($condition['field'] instanceOf QueryConditionInterface) {
        $this->conditions[$key]['field'] = clone($condition['field']);
      }
    }
  }

i did see a ould of other forums saying the same but they did not seem to solve the problem. any idea?

thanks
ricky