[FIX] stock: method do_prepare_partial takes into account moves in state 'waiting'

When scrapping received products, the state of the move will be switched back
from 'assigned' to 'waiting' in method 'recalculate_move_state'. These moves
must be taken into account in 'do_prepare_partial', which is called when
clicking on 'Transfer'.

Note that this bug would only appear if:
- reception in 2 steps is set
- the products are received without scrapping in the first step
- on the second step, we first scrap, then transfer. If we transfer,
  cancel, scrap and transfer, it works since the pack_operation_ids have been
  calculated correctly during the first click on 'Transfer'.

opw-640415

addons/stock/stock.py

@@ -1163,7 +1163,7 @@ class stock_picking(osv.osv):
             picking_quants = []
             #Calculate packages, reserved quants, qtys of this picking's moves
             for move in picking.move_lines:
-                if move.state not in ('assigned', 'confirmed'):
+                if move.state not in ('assigned', 'confirmed', 'waiting'):
                     continue
                 move_quants = move.reserved_quant_ids
                 picking_quants += move_quants