Code review comment for lp:~javier.collado/checkbox/bug990075

One pending thing to check is what happens in the presence of circular dependencies.
Since depth-first search stops when a job has already been inspected, I don't expect
any side effect like and infinite loop.

Looking at the code, it seems that they're already handled in the suites_prompt.py plugin
using checkbox.lib.resolver.Resolver, which actually seems to address topological order,
but I didn't use it because it wasn't used either in the original code (I guess there was
a good reason for that).

Hence, what should happen is that an exception is raised in checkbox.lib.resolver.Resolver
as it would have happened in the past.