added a special case fix for the loss db serialization for the scenario risk calc
added a special case fix for the loss db serialization for the scenario risk calc


Former-commit-id: 7af5ec9d58a6e2283d6c234f82697d49a5b19a8e
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine