Description:
------------
Apache2 crashes when call is made to execute prepared 
statement with null parameters.
Usign PDO-PostgreSQL

Apache 2.0
PostgreSql 8.1
PHP 5,1.6

Reproduce code:
---------------
$dbh=new PDO("pgsql:yourdb");
$sth = $dbh->prepare('SELECT * from "table" WHERE "field1"= ? AND "field2"= ?');
$sth->execute(array(null,null));

<crash>

Actual result:
--------------
Crash reporter output:



Thread 7 Crashed:
0   libpq.4.dylib       0x007b161e parseInput + 6
1   libpq.4.dylib       0x007b1eb6 PQgetResult + 31
2   libpq.4.dylib       0x007b2229 PQexecStart + 50
3   libpq.4.dylib       0x007b242d PQexec + 21
4   libphp5.so          0x020f18ab pgsql_stmt_dtor + 111
5   libphp5.so          0x020ed125 free_statement + 214
6   libphp5.so          0x022ebc06 
zend_objects_store_free_object_storage + 58
7   libphp5.so          0x022bddce shutdown_executor + 947
8   libphp5.so          0x022cc63d zend_deactivate + 226
9   libphp5.so          0x0227d4db php_request_shutdown + 
848
10  libphp5.so          0x0236cbcc php_handler + 2003
11  apache2             0x0001e430 ap_run_handler + 59 
(config.c:152)
12  apache2             0x0001e833 ap_invoke_handler + 87 
(config.c:366)
13  apache2             0x0000cb86 ap_process_request + 375 
(http_request.c:249)
14  apache2             0x00006e1d 
ap_process_http_connection + 297 (http_core.c:253)
15  apache2             0x0002ab62 ap_run_process_connection 
+ 59 (connection.c:43)
16  apache2             0x0002ae80 ap_process_connection + 
69 (connection.c:178)
17  apache2             0x0001b509 worker_thread + 545 
(threadpool.c:683)
18  libapr-0.0.dylib    0x00715f51 dummy_worker + 22 
(thread.c:106)
19  libSystem.B.dylib   0x90023d87 _pthread_body + 84