brotherton-erpnext/erpnext/patches/v10_0/set_currency_in_pricing_rule.py

from __future__ import unicode_literals
import frappe

def execute():
	frappe.reload_doctype("Pricing Rule")

	currency = frappe.db.get_default("currency")
	for doc in frappe.get_all('Pricing Rule', fields = ["company", "name"]):
		if doc.company:
			currency = frappe.get_cached_value('Company',  doc.company,  "default_currency")

		frappe.db.sql("""update `tabPricing Rule` set currency = %s where name = %s""",(currency, doc.name))