patch: invalid gain loss gl entry

erpnext/patches.txt

@@ -309,3 +309,4 @@ erpnext.patches.v13_0.update_dates_in_tax_withholding_category
 erpnext.patches.v14_0.update_opportunity_currency_fields
 erpnext.patches.v13_0.gst_fields_for_pos_invoice
 erpnext.patches.v13_0.create_accounting_dimensions_in_pos_doctypes
+erpnext.patches.v13_0.modify_invalid_gain_loss_gl_entries

erpnext/patches/v13_0/modify_invalid_gain_loss_gl_entries.py

@@ -0,0 +1,40 @@
+from __future__ import unicode_literals
+
+import frappe
+
+
+def execute():
+	purchase_invoices = frappe.db.sql("""
+		select
+			parenttype as type, parent as name
+		from
+			`tabPurchase Invoice Advance`
+		where
+			ref_exchange_rate = 1
+			and docstatus = 1
+			and ifnull(exchange_gain_loss, '') != ''
+		group by
+			parent
+	""", as_dict=1)
+
+	sales_invoices = frappe.db.sql("""
+		select
+			parenttype as type, parent as name
+		from
+			`tabSales Invoice Advance`
+		where
+			ref_exchange_rate = 1
+			and docstatus = 1
+			and ifnull(exchange_gain_loss, '') != ''
+		group by
+			parent
+	""", as_dict=1)
+
+	for invoice in purchase_invoices + sales_invoices:
+		doc = frappe.get_doc(invoice.type, invoice.name)
+		doc.docstatus = 2
+		doc.make_gl_entries()
+		for advance in doc.advances:
+			advance.db_set('exchange_gain_loss', 0, False)
+		doc.docstatus = 1
+		doc.make_gl_entries()