Fixed a pickling error in Python 2
Fixed a pickling error in Python 2


Former-commit-id: ea0913a7d15317ec24b4296bf36ad915e92542a3 [formerly 5e48cd200dd76d9f0021521bbc881ba2da28e854]
Former-commit-id: 24e9bf53caf9e9ef2ccce854a4f3fe58b02ca623
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine