message: Improve error message in ColocateResourceAndRefEdges.
diff: @@ -212,7 +212,9 @@ Status Member::EnsureCompatibilityAcrossResourceEdge(
  "Cannot place the graph because a reference or resource edge "
  "connects colocation groups with incompatible assigned devices: ",
  DeviceNameUtils::ParsedNameToString(src_root.assigned_device_name_),
  - " vs ", DeviceNameUtils::ParsedNameToString(assigned_device_name_));
  + " vs ", DeviceNameUtils::ParsedNameToString(assigned_device_name_),
  + ". The edge src node is ", src.name(), " , and the dst node is ",
  + dst.name());
  }
  if (DeviceNameUtils::AreCompatibleDevNames(src_root.requested_device_name_,
  