[p4] patch process and branching model

[Adrian Kalaveshi]

Greetings --

In a meeting today, I was involved in a nearly philosophical debate
about the process surrounding patch development and propagation.  In
general, I think there are two paths one can take here:

- Patches are released in a serialized and cumulative manner and work
  is performed in a single branch.  Each patch released to a customer
  contains all of the previous patches.

- Patches are atomic (though may have dependencies on each other) and
  work is done in multiple branches (one per customer, one per patch,
  or some other scheme that makes sense).  It's possible to deploy a
  single patch to a customer (without *every* patch before it).

I'm curious to learn which approach is more popular and, in the latter
case, what kind of automation your company employs to lessen the added
overhead.

Regards,
-adrian-