Remove overly aggressive packet processing

With the socket pooling, we no longer have to be as aggressive about
trying to get packets out of the socket buffer.  However, in a very
busy system of several hundred nodes, this aggressive processing
tends to produce larger python stacks and can exceed the default
1,000 limit.  We may have to resort to increasing the limit one day,
but for now this case can be avoided.

Change-Id: I83bdaa2d8ad464727a69e6ece064f51cd4318822