Take offline dialog has counts wrong

When a document that is a reference for othjer documents is taken offline a dialog informs us about it.
A similar, not identical, dialog called "Show referring documents" is obtained by clicking Documents action > Show referring documents...

Both present the documents in question rather accurately, but they get the counts wrong.

STEPS:
------

• as 'admin' on 'quickstart'
• under Documents, add a root folder 'base'
• add a new document of type 'Base Document' to 'base' (we name it basedoc)
• under Documents, under 'news', add one document of the 'News' type (we name it n0)
• link this document to the previous base document (within the Link field)
• from n0, do Document Actions > Copy and make nine (9) copies (n1, ..., n9)
• from basedoc, do Document Action > Show referring documents... and verify that 'This document is referred by 10 documents' appears in a dialog, which is correct.
• publish all of n0, ..., n9 and basedoc.
• from basedoc, open the Referring Documents dialog again

Now it's wrong: it says "This document is referred to by 22 documents, 20 are shown:". But it shows correctly the only ten (10) documents that are referring basedoc.

• alternatively to the previous step, you could also do, from basedoc, Publication Actions > Take offline... You would be presented with another similar, not identical, dialog where the documents that are shown are the right ones, but where the counts would still, be wrong.

The two dialogs resulting from the above last operations are attached as dlg1 and dlg2 respectively.