Advanced search fails to show tagset criteria when editing saved search

This is reproducible on the Drupal 7 demo.

1. Create a tagset (Favourite marsupial)
2. Tag a contact (Favourite marsupial = Kangaroo)
3 Create a smart group using that tagset (Kangaroo appreciators have Kangaroo as their favourite marsupial)
4, Try to edit the criteria for the smart group and the Favourite marsupial = Kangaroo criterion is lost

The workaround is to manually add it again and then save, but that's easily forgotten.

This occurs because while the tagsets are displayed separately to other tags, in the saved search they are all stored together. When retrieved from the saved search, the tagset tags need to be separated again.

The function that 'normalises' the tags so they are all stored together in the saved search is CRM_Contact_Form_Search_Advanced::normalizeFormValues(). On the form, normal tags are stored in an element named 'contact_tags' while tagset tags are stored in elements named 'contact_taglist[23]' where '23' is the Id of the tagset. normalizeFormValues() converts them all to parameters with name 'contact_tags' (the queries use the IN operator on the tag Ids and don't care if they are tagset tags).

What's needed is some code that reverses this. I will supply a patch to the function CRM_Contact_Form_Search_Advanced::normalizeDefaultValues() that ...

1. Does no harm if the $defaults don't need this processing
2. Looks at each 'contact_tags' default to see if it is a tagset tag
3. If one if found, moves the 'contact_tags' element to an array like 'contact_taglist[23]'
4. Cleans up the 'contact_tags' array