Preserve order of sale line in invoice

(transplanted from 41ec52ac100e4174ad9c94d59d8c856c4f3b612c)

sale.py

@@ -650,7 +650,7 @@ class Sale(ModelWorkflow, ModelSQL, ModelView):
 
         :param sale: the BrowseRecord of the sale
 
-        :return: a dictionary with invoice line as key
+        :return: a dictionary with invoiced sale line id as key
             and a list of invoice lines values as value
         '''
         line_obj = self.pool.get('sale.line')
@@ -718,12 +718,14 @@ class Sale(ModelWorkflow, ModelSQL, ModelView):
         with Transaction().set_user(0, set_context=True):
             invoice_id = invoice_obj.create(vals)
 
-        for line_id in invoice_lines:
-            for vals in invoice_lines[line_id]:
+        for line in sale.lines:
+            if line.id not in invoice_lines:
+                continue
+            for vals in invoice_lines[line.id]:
                 vals['invoice'] = invoice_id
                 with Transaction().set_user(0, set_context=True):
                     invoice_line_id = invoice_line_obj.create(vals)
-                sale_line_obj.write(line_id, {
+                sale_line_obj.write(line.id, {
                     'invoice_lines': [('add', invoice_line_id)],
                     })