XEP-0030 Service Discovery: 'node' attribute in response NOT mandatory
XEP-0030: "If the request included a 'node' attribute, the response SHOULD mirror the specified 'node' attribute to ensure coherence between the request and the response."
Mirroring the 'node' attribute is not mandatory. Tkabber does not mirror it. But Gajim ignores the response when the 'node' attribute is not mirrored:
./src/common/caps.py in function _capsDiscoCB: if not node.startswith(contact.caps_node + '#'): return