[Rock-dev] Flavours, freezes, updates

[Traveler Hauptman]

I don't really have time to join the discussion properly, but I'd like 
to say that I have thought about this topic quite a bit in a non-rock 
context (but still robotics). We have a large number of repositories 
under development, all with external dependencies. Our build system is 
built directly on cmake scripts but tries to solve the same set of 
problems as autoproj.

I arrived at a similar point as Jakob. Repo heads are easy to think 
about and are what developers work with but the only way to provide any 
guarantees to a down-stream user is to mark the graph of exact commits 
that create a "working" system.

-Traveler