added test to cover change in get_db_session()
added test to cover change in get_db_session()


Former-commit-id: 2a02cab876ed599db89e24b3e2e1ac9a4271dba3 [formerly f9ef0151618ffe29bfd67213e496608636b35b8a]
Former-commit-id: 89d651697782ea41fe76cd738c4e05af83df794a
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine