Comment 1 for bug 591327

Regarding the PS: testr failing will show all the attachments for failures, its the default serialisation to show everything.

The proposal is broadly ok. A few tweaks:
 - a method please, not an attribute (allows lazy generation more obviously)
 - no need to guard against old Mismatch objects, change the base class, this is marked experimental in our docs.
 - perhaps a dict rather than tuples ?
 - also, given the TestCase may already have the names used, it will need to append -1 -2 etc to names that are already used. Or something like that.

+1 on the overall concept though - I likes.