Name lookup assertion
After the 7e8eb285 merge:
==2140== Use of uninitialised value of size 8
==2140== at 0x42339A: knot_response_compress_dname (wire.h:913)
==2140== by 0x42916E: knot_rrset_to_wire_aux (rrset.c:342)
==2140== by 0x429A18: knot_rrset_to_wire (rrset.c:1119)
==2140== by 0x423083: knot_response_try_add_rrset (response.c:214)
==2140== by 0x423E1E: knot_response_add_rrset_authority (response.c:599)
==2140== by 0x41BA68: ns_put_authority_soa (name-server.c:909)
==2140== by 0x41E316: knot_ns_answer_normal (name-server.c:1892)
==2140== by 0x4117A0: zones_normal_query_answer (zones.c:2145)
==2140== by 0x409BFD: udp_handle (udp-handler.c:187)
==2140== by 0x409DF3: udp_recvfrom_handle (udp-handler.c:312)
==2140== by 0x40A02D: udp_reader (udp-handler.c:597)
==2140== by 0x40A1B5: udp_master (udp-handler.c:633)
knotd: libknot/nameserver/name-server.c:1922: ns_answer_from_node: Assertion `previous == ((void *)0)' failed.
The uninitialised value is probably related to the wrong node lookup.