Hi,
I just updated from python-Stix 1.2.0.0 to with a 'pip install --update stix' and set_id_namespace breaks on any script that sets a custom namespace. Pip installed 1.2.0.1dev3 and it broke. Any of the 1.2.0.1devX versions are broken. I had to manually rollback to python-stix 1.2.0.0 (and the matching Cybox) for the scripts to work again.
Cheers
Terry MacDonald