[dataimport] remove threading support from SQLGenObjectStore
It's untested and does not actually work at the moment with nb_threads > 1.
related to #9177565.
Samuel Trégouët <samuel.tregouet@logilab.fr> [Thu, 03 Dec 2015 14:55:10 +0100] rev 10984
[dataimport] prepare_insert_entity should not crash with SQLGenObjectStore
grafted from 1079d68130e1e780791ceb2050e8a8b7a910f48d (3.22)
related to #9177565.