[trunk/7.0]OE chatter's tracking doesn't support m2m or one2many

I have a model which inherits mail.thread. On this model I have enabled track_visibility='onchange' on many of the fields.
The widget logs all changes done to fields.char, fields.selection in a way that is natural.
When it comes to fields.many2many and fields.one2many, what is logged is a string representation of the list of the foreign object ids.

Steps to reproduce:
* Create a module with an object which inherits 'mail.thread', add a many2many or a one2many relational field.
* Create the view with the fields and the chatter section
* Modify the field
* Save changes

Expected output:
The chatter will log something along the lines of:
Test object:
* first entry.. * second entry
              → * third entry
                * fourth entry

or:
Test object:
* Added:
  * second entry
  * third entry
  * fourth entry
* Removed:
  * first entry

Actual output:
The chatter will log something along the lines of:
Test object: [1] → [2, 3, 4]

Versions:
server: r5248
addons: r9856