Segfault when creating topics with composite inherited key

[tonichedgehog]

Hi, the below IDL and python script produces a segfault when creating the second toipc:

module ns {

@nested
struct Identity {
  long f1;
  long f2;
};

@topic
struct Base {
  @key Identity id;
};

@topic
struct Derived : Base {
  long val;
};

};

idlc -x final -l py input.idl

import cyclonedds as dds
from ns import Base, Derived

if __name__ == '__main__':

    dp = dds.domain.DomainParticipant()

    t1 = dds.topic.Topic(dp, 't1', Base)
    t2 = dds.topic.Topic(dp, 't2', Derived)

Using cyclonedds from master, 00c63c34, and cyclonedds-python 8a1486bd33cc6797831567566b154db222adf6b5 on Linux.