Clear the cache when converting a category to a tag, so category is removed from the list of cats
|Reported by:||warwickp||Owned by:||ryan|
Props: Andy Skelton
When a category is converted to a tag, the category should be removed from the list of categories that populates the category list on /wp-admin/post-new.php
The converted category however persists in the cache, unless the cache is deleted, which this patch achieves.