merge_tree: further implement mergeWithLocal
merge_tree: further implement mergeWithLocal

Netsend/PerspectiveDB,Netsend/persdb,Netsend/PerspectiveDB,Netsend/mastersync,Netsend/mastersync,Netsend/PerspectiveDB,Netsend/persdb,Netsend/mastersync,Netsend/persdb