[FIX] purchase: ignore quantity sign when computing move amount_currency

Since 348c371e, the quantity is negative
for out moves. Ignore the sign when computing the amount_currency value.

addons/purchase/models/stock.py

@@ -56,12 +56,11 @@ class StockMove(models.Model):
         self.ensure_one()
 
         rslt = super(StockMove, self)._generate_valuation_lines_data(partner_id, qty, debit_value, credit_value, debit_account_id, credit_account_id)
-
         if self.purchase_line_id:
             purchase_currency = self.purchase_line_id.currency_id
             if purchase_currency != self.company_id.currency_id:
                 purchase_price_unit = self.purchase_line_id.price_unit
-                currency_move_valuation = purchase_currency.round(purchase_price_unit * qty)
+                currency_move_valuation = purchase_currency.round(purchase_price_unit * abs(qty))
                 rslt['credit_line_vals']['amount_currency'] = rslt['credit_line_vals']['credit'] and -currency_move_valuation or currency_move_valuation
                 rslt['credit_line_vals']['currency_id'] = purchase_currency.id
                 rslt['debit_line_vals']['amount_currency'] = rslt['debit_line_vals']['credit'] and -currency_move_valuation or currency_move_valuation