Patch to LinkHoldersArray

For several good reasons DPL uses an internal clone of the MediaWiki parser.

In this context you may observe a php error message telling you that there was a problem in LinkHoldersArray.php.

By applying the following patch to (wiki_home)/includes/parser/LinkHoldersArray.php you can fix this problem:

Search for the beginning of function 'merge' and add the following code lines:

if (!isset($this->interwikis)) {
   $this->internals = array();
   $this->interwikis = array();
   $this->size = 0;
   $this->parent  = $other->parent;
}

In MediaWiki 1.16.2 you have to insert this text block after line #24; in other versions of MediaWiki the line number may be different.