Do not override deleted record instances by related records

(grafted from 5b67535bb4cdf07df76c15e6fb4b425f44f4ad23)

--HG--
branch : 6.0

trytond/trytond/model/modelsql.py

@@ -1150,9 +1150,10 @@ class ModelSQL(ModelStorage):
                 if (not hasattr(Model, 'search')
                         or not hasattr(Model, 'write')):
                     continue
-                records = get_related_records(Model, field_name, sub_ids)
-                if records:
-                    Model.write(records, {
+                related_records = get_related_records(
+                    Model, field_name, sub_ids)
+                if related_records:
+                    Model.write(related_records, {
                             field_name: None,
                             })
 
@@ -1160,9 +1161,10 @@ class ModelSQL(ModelStorage):
                 if (not hasattr(Model, 'search')
                         or not hasattr(Model, 'delete')):
                     continue
-                records = get_related_records(Model, field_name, sub_ids)
-                if records:
-                    Model.delete(records)
+                related_records = get_related_records(
+                    Model, field_name, sub_ids)
+                if related_records:
+                    Model.delete(related_records)
 
             for Model, field_name in foreign_keys_tocheck:
                 with Transaction().set_context(