Must be zero bit set on queries with multiple forwarders

[briggs at encompasserve.org]

I have a problem with BIND.  It manifests in at least 9.2.1 and 9.2.3
and involves forwarders.  The BIND software emits malformed queries.

I have not verified whether the issue is platform-specific.  We're
running on Solaris 7.

I have packet traces that show that the BIND server is setting a bit
within the must-be-zero bits within DNS queries going to the forwarders.

The behavior is consistent and reproducible and appears to affect
every zone that uses multiple forwarders.

In the case at hand, we have a zone defined as type forward:

	zone "245.141.in-addr.arpa" {
		type forward;
		forwarders {
			141.245.68.6;
			141.245.68.7;
			141.245.245.242;
			141.245.245.241;
		};
	};