[publican-list] clean_ids duplicates IDs in <listitem> tags

[David O'Brien]

I don't usually do this, but I  had cause to do it today.

I put an ID in two <listitem> tags because I needed to refer to them 
later, using an <xref>. The original ID was just invented, e.g., fred, 
and clean_ids converted it to what it "should" be (based on section, 
title, etc.).

Subsequent use of clean_ids, however, resulted in duplication of the ID, 
so instead of "sect-My_Section-My_List", it created 
"sect-My_Section-My_List-sect-My_Section-My_List". Each use of clean_ids 
added another level to the ID.

Is this fixable? Is there a better way to do it?

Thanks
-- 

/David