Allow to search on default UoM of stock lot

Since e49aaf8553e1, default UoM of "Lots by Locations" has a searcher using
the default UoM of the stock lot.

Closes #12583
(grafted from 09a961f1f5e27c8f0787bea29c881ee67c9163a6)

--HG--
branch : 6.0

modules/stock_lot/stock.py

@@ -79,7 +79,7 @@ class Lot(ModelSQL, ModelView, LotMixin, StockMixin):
         'get_quantity', searcher='search_quantity')
     default_uom = fields.Function(
         fields.Many2One('product.uom', "Default UOM"),
-        'on_change_with_default_uom')
+        'on_change_with_default_uom', searcher='search_default_uom')
     default_uom_digits = fields.Function(fields.Integer("Default Unit Digits"),
         'on_change_with_default_uom_digits')
 
@@ -108,6 +108,11 @@ class Lot(ModelSQL, ModelView, LotMixin, StockMixin):
         if self.product:
             return self.product.default_uom.id
 
+    @classmethod
+    def search_default_uom(cls, name, clause):
+        nested = clause[0][len(name):]
+        return [('product.' + name + nested, *clause[1:])]
+
     @fields.depends('product')
     def on_change_with_default_uom_digits(self, name=None):
         if self.product: