Patch for no bgp default ipv4-unicast

[David Croft]

Hello,

I have submitted a patch that allows RtConfig to function correctly on
a router configured with "no bgp default ipv4-unicast".

It causes afi ipv4.unicast not to be considered "default" when
-no_default_afi is specified on the command line. This in turn causes
CiscoConfig to activate the address family for IPv4 peers and
configure policy under the address family instead of global BGP config
mode (which previously resulted in "% Policy commands not allowed
without an address family").

http://irrtoolset.isc.org/ticket/13

David