Description:
------------
This doesn't happen often, but it does happen sometimes when the database server 
interrupts the connection during a query. Seems to be related to the fact that 
libmysqlclient's mysql_query() may return success, even if an error occurred, as 
described at:

http://dev.mysql.com/doc/refman/5.5/en/null-mysql-store-result.html

Test script:
---------------
$resource = mysql_query('SELECT test FROM test');
if ($resource === true) {
    throw new Exception('mysql_query() returned true for SELECT');
}

Expected result:
----------------
An exception should not be thrown, because the documentation for mysql_query() at 
php.net clearly states that a SELECT query will only ever return false or a 
resource.

Actual result:
--------------
An exception is thrown, because mysql_query() returns true with a SELECT query.