Fix error introduced in Change Ieae80c63e391cfb1af61841a6badd51b87d00cfe

The {{NAMESPACE}} magic word is broken by the above commit, since it uses
the function name "mwnamespace" in order to not conflict with the PHP 5.3
namespace keyword.

Change-Id: I807c9b89c101db289c0ec47593c18b0d1dc2260b