Description:
------------
mysqli_connect() no longer accepts false/null for the socket parameter. It interprets it as an empty string and as a result fails to find the socket and therefore connect.

Previous versions used to ignore false/null and just use the hostname etc to connect.

The reason I am not just changing the call to

$db = mysqli_connect($host, $username, $password, $database);

is because this code is from PEAR::DB and this change would be quite major. See my bug: 
http://pear.php.net/bugs/bug.php?id=2960

as danielc points out: "most PHP functions gladly
accept false/null for optional string arguments without causing problems"



Reproduce code:
---------------
<?php

$db = mysqli_connect($host, $username, $password, $database, null, null);

?>
same result with 

<?php

$db = mysqli_connect($host, $username, $password, $database, false, false);

?>


Expected result:
----------------
a valid connection

Actual result:
--------------
following error:
Can't connect to local MySQL server through socket '' (2)