fix: Return against internal purchase invoice (backport #33635) (#33658)

fix: Return against internal purchase invoice (#33635)

(cherry picked from commit 906ad10)

Co-authored-by: Deepesh Garg <deepeshgarg6@gmail.com>

erpnext/controllers/accounts_controller.py

@@ -394,7 +394,7 @@ def validate_inter_company_reference(self):
 				self.get("inter_company_reference")
 				or self.get("inter_company_invoice_reference")
 				or self.get("inter_company_order_reference")
-			):
+			) and not self.get("is_return"):
 				msg = _("Internal Sale or Delivery Reference missing.")
 				msg += _("Please create purchase from internal sale or delivery document itself")
 				frappe.throw(msg, title=_("Internal Sales Reference Missing"))