diff -r c1860f118efd move.py
--- a/trytond/trytond/modules/stock/move.py	Wed Nov 07 12:14:26 2018 +0100
+++ b/trytond/trytond/modules/stock/move.py	Wed Nov 07 12:18:14 2018 +0100
@@ -748,6 +748,10 @@ class Move(Workflow, ModelSQL, ModelView):
             return to_pick
         return to_pick
 
+    @staticmethod
+    def lock_stock_move():
+        return True
+
     @classmethod
     def assign_try(cls, moves, with_childs=True, grouping=('product',)):
         '''
@@ -780,34 +784,35 @@ class Move(Workflow, ModelSQL, ModelView):
         companies = {m.company for m in moves}
         stock_date_end = Date.today()
 
-        if database.has_select_for():
-            for company in companies:
-                table = cls.__table__()
-                query = table.select(Literal(1),
-                    where=(table.to_location.in_(location_ids)
-                        | table.from_location.in_(location_ids))
-                    & table.product.in_(product_ids)
-                    & (table.company == company.id),
-                    for_=For('UPDATE', nowait=True))
-
-                PeriodCache = Period.get_cache(grouping)
-                if PeriodCache:
-                    periods = Period.search([
-                            ('date', '<', stock_date_end),
-                            ('company', '=', company.id),
-                            ('state', '=', 'closed'),
-                            ], order=[('date', 'DESC')], limit=1)
-                    if periods:
-                        period, = periods
-                        query.where &= Coalesce(
-                            table.effective_date,
-                            table.planned_date,
-                            datetime.date.max) > period.date
-
-                with connection.cursor() as cursor:
-                    cursor.execute(*query)
-        else:
-            database.lock(connection, cls._table)
+        if cls.lock_stock_move():
+            if database.has_select_for():
+                for company in companies:
+                    table = cls.__table__()
+                    query = table.select(Literal(1),
+                        where=(table.to_location.in_(location_ids)
+                            | table.from_location.in_(location_ids))
+                        & table.product.in_(product_ids)
+                        & (table.company == company.id),
+                        for_=For('UPDATE', nowait=True))
+
+                    PeriodCache = Period.get_cache(grouping)
+                    if PeriodCache:
+                        periods = Period.search([
+                                ('date', '<', stock_date_end),
+                                ('company', '=', company.id),
+                                ('state', '=', 'closed'),
+                                ], order=[('date', 'DESC')], limit=1)
+                        if periods:
+                            period, = periods
+                            query.where &= Coalesce(
+                                table.effective_date,
+                                table.planned_date,
+                                datetime.date.max) > period.date
+
+                    with connection.cursor() as cursor:
+                        cursor.execute(*query)
+            else:
+                database.lock(connection, cls._table)
 
         pblc = {}
         for company in companies: