Restored the subtasks functionality
Restored the subtasks functionality


Former-commit-id: 141e49f7ff9dbf83e04ae9ae05ac9af48a7d00c6 [formerly 141e49f7ff9dbf83e04ae9ae05ac9af48a7d00c6 [formerly 4344001ffb0f21f3cb2b7f5d2fe8f0ca6bfeb0d8]]
Former-commit-id: 22b953be251f08aeedc31cff0416aad5aff471c8
Former-commit-id: bd4dd88ae62de303135ac57965d928eadc9cba1a
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine