Reset actual quantity when copying line

issue10874
review350841002
(grafted from 7f21b6d067a413830bc51fb982b5885daccf9650)

--HG--
branch : 6.0

purchase.py

@@ -1767,6 +1767,7 @@ class Line(sequence_ordered(), ModelSQL, ModelView):
         default.setdefault('moves_ignored', None)
         default.setdefault('moves_recreated', None)
         default.setdefault('invoice_lines', None)
+        default.setdefault('actual_quantity')
         return super().copy(lines, default=default)