Set src_group_id when splitting MultiPointSources [skip CI]
Set src_group_id when splitting MultiPointSources [skip CI]


Former-commit-id: e4f08d74fa8da5ff5ed18f4537db3f68734387c2 [formerly 8fe277b604d02f7e94b388f8419a6bbeee58005d]
Former-commit-id: 9e60870608d9317d13eb2fb56e9cec92179a2758
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine