Grigorii Demidov authored May 31, 2016 and Petr Špaček committed Feb 23, 2017

dnspython library by default coalesces RRsets of same type into one and
automaticaly deduplicates equicalent RRs inside one RRset.
This prevented Deckard from testing DNS messages with duplicate RR.

To prevent this, all DNS messages are now parsed using option
one_rr_per_rrset=True. This setting may create multiple RRsets
of the same type but it seems okay for Deckard because the comparison
algorithms compare individual RRs and ignore how they are distributed
among RRsets.