Description:
------------
I run some code 5 million itteration yesterday, today I change my string building to use single quotes and the dot operator. That version was able to do aprox 25k itterations then the script died due memory leak.

Reproduce code:
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#           Makign a string like this leaks NOT memory

#         $lInsert = "Insert into {$this->mTable} (datetime,entity_id,entity_type,domain,country,location,raws,uniques)" .
#                    " values ('{$this->getDateTime()}',{$this->getEntityId()},{$this->getEntityType()},{$this->getDomain()}," .
#                    "{$this->getCountry()},{$this->getLocation()},{$this->getRaws()},{$this->getUniques()});";


#           Making a string liek this leaks memory when doign execute
         $lInsert = 'Insert into '.$this->mTable.' (datetime,entity_id,entity_type,domain,country,location,raws,uniques)' .
                   ' values ("'.$this->getDateTime().'",'.$this->getEntityId().','.$this->getEntityType().','.$this->getDomain().',' 
                   .$this->getCountry().','.$this->getLocation().','.$this->getRaws().','.$this->getUniques().');';

#         $lInsert = "Insert into {$this->mTable} (datetime,entity_id,entity_type,domain,country,location,raws,uniques)" .
#                   " values ('{$lTimeStamp}',{$lEntityId},{$lEntityType},{$lDomain},{$lCountry},{$lLocation},{$lRaws},{$lUniques})";
#
      print memory_get_usage()."\n";
                   
      $lStatement =& $this->mDbh->prepare($lInsert);
      
      if (MDB2::isError($lStatement)){
           error_log($lStatement->getMessage().';query:'.$lInsert.' '.$lStatement->userinfo);
         $lResult = false;
       } else {
         $lResult =& $lStatement->execute();
         $lStatement->free();
       }


Expected result:
----------------
See code comments

Actual result:
--------------
see code comments