Product Pricelist Alternative

This module extends Odoo's price lists (product.pricelist) with the idea of alternative price lists. On a price list form you get a new "Alternative Pricelists" section where you can select other price lists to compare against. When Odoo computes a product's price, it looks at the price rule that applies in the main price list and, if that rule's new "Alternative Pricelist Policy" is set to "Use lower price", it also computes the price in each alternative price list and keeps the lowest one. If the policy is "Ignore alternatives", the alternatives are not used for that rule.

The new policy field appears on price rules: in the rule form (after the fixed price field), in the rules list, and in the rules list shown from a product. A smart button "Alternative to Pricelist" on the price list form shows how many other price lists use the current one as an alternative, and clicking it opens that list.

Two safety checks are added: an alternative price list cannot contain rules whose price is computed from another price list (a validation error is raised), and the same restriction is checked when you add alternatives to a price list. Product variants are handled so that the correct variant is used when comparing alternative prices.