[Bucardo-general] Alternative to onetimecopy with bucardo 5.1.2

[sym39]

> To do this, I though I could create a sync with database A and B as 
> "source" and set the conflict_strategy of the sync to onetimecopy. But 
> initial data is not filled, most probably because of the issue 
> described here : https://github.com/bucardo/bucardo/issues/37 "onetime 
> Does Not Work in 4.99.6 #37 "
More precisely, onetimecopy is set to "2" and conflict_strategy is set 
to "bucardo_latest"