Code review comment for lp:~jameinel/bzr/2.1.0b2-471193-st-and-chk-map

This fixes a critical bug for the 2.1.0b2 series.

Basically, there are some code paths by-which regular tuples can end up where we may not want them. We *could* change all of our apis to auto-cast, but that will end up negating the performance advantage. (As then you have 2 objects a tuple *and* a StaticTuple, referring to the same things.)

However, we need a migration strategy. So for now, I'm adding a debug flag that I can set, similar to '-Dhpss'. When set, I chose to cause an exception rather than just printing a traceback. We can change our minds later.