fix: Discount and taxes in return document should follow the reference document

[nabinhait]

If a credit note is created against a sales invoice, the credit note should follow the same discount (based on the pricing rule) and tax template as in the original sales invoice.

Previously, if we changed the discount on the pricing rule after creating the original sales invoice, the system overwrites the discount on the credit note based on the updated pricing rule.

Similarly, the item tax template and tax table is overwritten based on the updated item tax template in the Item master.

[ruthra-kumar]

This causes

erpnext/erpnext/controllers/sales_and_purchase_return.py

Lines 124 to 127 in f28c692

	frappe.throw(
	_("Row # {0}: Rate cannot be greater than the rate used in {1} {2}").format(
	d.idx, doc.doctype, doc.return_against
	)

to throw

[nabinhait]

This causes

erpnext/erpnext/controllers/sales_and_purchase_return.py

Lines 124 to 127 in f28c692

	frappe.throw(
	_("Row # {0}: Rate cannot be greater than the rate used in {1} {2}").format(
	d.idx, doc.doctype, doc.return_against
	)

to throw

When are you getting this validation? Are you manually changing the item rate?

[ruthra-kumar]

Are you manually changing the item rate?

No.
Just try submitting the Credit Note. Above validation will throw.