Refactored test code in parser_fragility_model_unittest, removed try/catch and used the context manager in all tests.
Refactored test code in parser_fragility_model_unittest, removed try/catch
and used the context manager in all tests.


Former-commit-id: f3fefad0e04e46fa6d19624125e20ffd2403be6d
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine