cached rr not provided to recursive clients

I have noticed that bind 9.2.3, albeit having the rr's in the cache as a
glue from parent, doesn't provide it to recursive clients, but only to
nonrecursive (dig +norec), in case authoritative servers are down.

Most probably bind is trying to verify with the authoritative servers,
and without their reply it refuses to provided the data to but only to
recursive clients.

Can someone elaborate what are the conditions/verifications/checks
required to provide recursive clients cached rrs'? What is the reasoning
behind this behavior?

This seems to be a topic of a minor interest, since I have raised
several times without much success, but I think I am not the first guy
who dumped the cache and see the rr data there, wondering why bind
doesn't provide it. Are those non-responding authoritative nameservers
considered lame? No, not for bind9 they are not lame since it doesn't
log them in the lame.log...

Ladislav