Code review comment for lp:~blake-rouse/maas/fix-1602721

It's too bad we have to hack around piston in this way. I think it would be acceptable to land this, but I'd like to see what others think, too. (Is this the best workaround we can think of? Should we consider a monkey patch, followed by submitting a patch upstream?)

The comment in the test for __eq__ is a code smell; I think the test either needs more testing to cover all the possible combinations, or be changed to be what we expect Piston to do. See comment below.