engine:
engine:

`_collect_source_model_paths` now returns a duplicate-free list of
source paths.


Former-commit-id: 329edb0588cceb26548881ac8235d2b082528d86 [formerly 17771e9b7572eaf60964fb420a020a4e88b2b14b]
Former-commit-id: d8fd29378919e50e4cd31e1d153755661a5a4c0a
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine