Fixes [#31645] Removing tags from a component item deletes all ucm_conte...

...nt items with the same core_content_item_id

Fixes http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=31645

Also requires function update in libraries/cms/helper/tags.php
https://github.com/joomla/joomla-cms/pull/1727