Description:
------------
When using static variables and the .= operand, the static variable doubles itself.

Reproduce code:
---------------
function test()
{
   static $test = '';
   $test .= 'lala|';
   echo $test;
}

test();
test();
test();

Expected result:
----------------
lala|lala|lala|

Actual result:
--------------
lala|lala|lala|lala|lala|lala|