Code review comment for lp:~rvb/maas/bug-1384001-redux-2

On Tuesday 28 Oct 2014 17:21:59 you wrote:
> I know it doesn't fit into Python's exception model very well, but then
> Python's exception model doesn't allow for concurrent exceptions in a
> single thread. It's a sign that we ought to move error-handling code closer
> to the call-site. The division between synchronous and asynchronous code
> is, I think, partially responsible.

When Raph and I discussed this, for trunk we agreed that we'd remove
MultipleFailures entirely (I believe you added it because of the multiple node
start-up stuff) and handle errors declared in the AMP message at the callsites
themselves. General errors should still get handled in the middleware.