Repost: Fix multi-message IXFR

[James Raftery]

Bob,

Would you please consider my IXFR fix for the next DNSPython release?

The attached patch:

* fixes IXFR processing where the deltas span multiple messages, where the

IXFR state machine would be mistakenly reset and raise spurious FormError

exceptions

* adds text to FormError exception raised when there's no answer or the

first RRset isn't for the name we asked for

* fixes the serial number check to recognise serials lower than ours as

meaning there's no data to read (e.g. if we send an IXFR query with a

serial higher than that of the remote party)

Thanks,

james

( Originally sent in April 2012: http://permalink.gmane.org/gmane.comp.python.dnspython.bugs/41 )