Fixed bug: the stats must be stored as a string, not an array of strings [skip hazardlib][demos]
Fixed bug: the stats must be stored as a string, not an array of strings [skip hazardlib][demos]


Former-commit-id: d75792bca362bff60509d6f8ccb01b39b0db0548
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine