fix: incorrect valuation rate for items from different warehouses in Gross Profit (backport #42330)

[mergify]

Scenario

Consider an Item with Negative stock enabled and currently has no stock left in any warehouse and the valuation rate of that item is 1900 /-

1. Make an Invoice from 'Warehouse 1'
2. Change the valuation rate in Item Master to 1800/-
3. Make another Invoice from 'Warehouse 2'

Issue

Gross Profit incorrectly reported valuation rate of 1900/- for both the invoices.

Expected

Gross Profit should used below valuation rates:

Invoice	Valuation Rate
Invoice 1	1900
Invoice 2	1800

Cause

get_average_buying_rate was memoizing based on item_code.

erpnext/erpnext/accounts/report/gross_profit/gross_profit.py

Lines 714 to 731 in 61daa31

	def get_average_buying_rate(self, row, item_code):
	args = row
	if item_code not in self.average_buying_rate:
	args.update(
	{
	"voucher_type": row.parenttype,
	"voucher_no": row.parent,
	"allow_zero_valuation": True,
	"company": self.filters.company,
	}
	)
	if row.serial_and_batch_bundle:
	args.update({"serial_and_batch_bundle": row.serial_and_batch_bundle})
	average_buying_rate = get_incoming_rate(args)
	self.average_buying_rate[item_code] = flt(average_buying_rate)

Fix

get_average_buying_rate will memoize results based on (item_code, warehouse)

---

This is an automatic backport of pull request #42330 done by Mergify.

[mergify]

Cherry-pick of 577ce5c has failed:

On branch mergify/bp/version-15-hotfix/pr-42330
Your branch is ahead of 'origin/version-15-hotfix' by 1 commit.
  (use "git push" to publish your local commits)

You are currently cherry-picking commit 577ce5ccd4.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   erpnext/accounts/report/gross_profit/test_gross_profit.py

no changes added to commit (use "git add" and/or "git commit -a")

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[frappe-pr-bot]

🎉 This issue has been resolved in version 15.30.0 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀