Why is libreoffice not incrementing my document’s Revision number on save?

Build ID: 7e4286b58adc75a14f6d83f53a03b6c11fa2903

I inserted the field “DocInformation” → “Revision number” into my document. At the documentation on the DocInformation tab, a “Document number” type is documented. I assume that the online documentation meant to say “Revision number” instead of “Document number” here. It is documented here that “Modified” is to be updated every time the document is saved.

The file I am editing is a .doc, File → Properties says “MS Word document”. Also, the Properties window also shows a “Modified” date of “11/26/2012, 16:02:00” and a “Revision number” of “15”. I have saved the document multiple times (on today’s date of 2013-09-09). I expect the Modified date to increase as well as the Revision number.

How can I forcefully increment the version number or update the Modified date? I must save this back to MS Word document format. I suppose I could try saving it to .odt, editing the XML there, and then converting back, but that just seems wrong.