Small refactoring of the logic tree tests [skip hazardlib]
Small refactoring of the logic tree tests [skip hazardlib]


Former-commit-id: 96fd173ec150a3813362be54705e293117a10eec [formerly 96fd173ec150a3813362be54705e293117a10eec [formerly b8ab8f3e1affb73cbbdadb91fc98daec90639494]]
Former-commit-id: 88ca327d6f3667325266eb967026fee7e3896744
Former-commit-id: 582aebd8dbef2f32668ef039374ba9081726181f
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine