We have a customer whose base unit for selling stuff is in thousands.  However stock can be as low as 0.001 thousands, but that last decimal place isn't displayed in the stock warning.

As you'll see from the example of "actual behaviour" below this is confusing.

Impacted versions:
- 8.0

Steps to reproduce:
- Install product and sale
- Create a unit of measure with:
  - Name: Thousand(s)
  - Product Category: Unit
  - Type: Bigger than the reference Unit of Measure
  - Bigger Ratio: 1000
  - Rounding Precision: 0.00100
- Create a product 'Widget' with
  - type = Stockable Product
  - UoM = Thousand(s)
- Create a Quotation
- Add to the Sales Order a line
- Choose Product: Widget
- Change Quantity to: 0.001 Thousand(s)

Current behavior:

Configuration Error!

```
Not enough stock ! : You plan to sell 0.00 Thousand(s) but you only have 0.00 Thousand(s) available !
The real stock is 0.00 Thousand(s). (without reservations)
```

Expected behavior:

Configuration Error!

```
Not enough stock ! : You plan to sell 0.001 Thousand(s) but you only have 0.000 Thousand(s) available !
The real stock is 0.000 Thousand(s). (without reservations)
```

""" Verify the route of the product based on the warehouse
            return True if the product availibility in stock does not need to be verified,
            which is the case in MTO, Cross-Dock or Drop-Shipping
        """
        is_available = False
        product_routes = self.route_id or (self.product_id.route_ids + self.product_id.categ_id.total_route_ids)
        
        wh_mto_route = self.order_id.warehouse_id.mto_pull_id.route_id
        if wh_mto_route and wh_mto_route <= product_routes:
            is_available = True
        else:
            mto_route = False
            try:
                mto_route = self.env['stock.warehouse']._get_mto_route()
            except UserError:
                
                pass
            if mto_route and mto_route in product_routes:
                is_available = True
        
        if not is_available:
            for pull_rule in product_routes.mapped('pull_ids'):
                if pull_rule.picking_type_id.sudo().default_location_src_id.usage == 'supplier' and\
                        pull_rule.picking_type_id.sudo().default_location_dest_id.usage == 'customer':
                    is_available = True
                    break
        return is_available