https://etherpad.openstack.org/p/mitaka-heat-break-stack-barrier Right now, dependencies don't cross stack boundaries. That leads to weird behaviour when you start using nested stacks to break up your application into more maintainable components. What if we were to break down the barriers between nested stacks and treat a whole tree of stacks as one giant dependency graph? Or at least split the update and cleanup phases of nested stack updates. (Note: Phase 1 of Convergence is a likely prerequisite.)
