Empty Values are converted to null by class-ixr.php

[nprasath002]

I tried to fix the following bug
http://core.trac.wordpress.org/ticket/10599
Found out when you send and empty value via xmlrpc
it converts it to null value.
Say you send and array of arguments for mw_editpost, set
$content_structmt_keywords? = ;
IXR client passes a null value instead of an empty value.

In mw_post method consider this statement
$tags_input = isset( $content_structmt_keywords? ) ? $content_structmt_keywords? : null;

Even if you send an empty value this statement fails because $content_structmt_keywords? is set to null by IXR client.