[REF]stock_auto_move: fix action_action()

**Use case**: doing a reception operation in two steps where the moves on
the second step are set to be automatic (using the push rule in this
case), and the reception is done partially.
**Expected Result**: When doing a first reception step partially a back
order is created, and we expect the second step to have a back order for
the remaining qty as well.
**Current behavior**: The correct move is processed automatically but no
backorder is created. The reason for that behavior is we processing the
move directly (i.e calling `action_done` of the `stock.move`) without
going through the normal process (i.e processing the second step
picking).
**The solution to the problem**: The processing the of the automatic
stock move should follow the same behavior as done from the user interface.
I've added a new function in `stock.picking` model called
`_transfer_pickings_with_auto_move` to simulate the same behavior this
function is called inside the `action_assign` of the stock move instead
of calling the `action_done` of the move.

stock_auto_move/models/__init__.py

@@ -1,6 +1,8 @@
 # -*- coding: utf-8 -*-
+# -*- coding: utf-8 -*-
 from . import stock_move
 from . import procurement_rule
 from . import procurement_order
 from . import stock_location_path
 from . import stock_pack_operation
+from . import stock_picking

stock_auto_move/models/stock_move.py

@@ -21,7 +21,7 @@ def action_assign(self, no_prepare=False):
         todo_pickings = moves.mapped('picking_id')
         # We create packing operations to keep packing if any
         todo_pickings.do_prepare_partial()
-        moves.action_done()
+        todo_pickings._transfer_pickings_with_auto_move()
 
     @api.multi
     def action_done(self):

stock_auto_move/models/stock_picking.py

@@ -0,0 +1,27 @@
+# -*- coding: utf-8 -*-
+# Copyright 2017 ACSONE SA/NV
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
+
+from openerp import api, models
+
+
+class StockPicking(models.Model):
+
+    _inherit = 'stock.picking'
+
+    @api.multi
+    def _transfer_pickings_with_auto_move(self):
+        """This function is meant to simulate what a user would normally
+        transfer a picking from the user interface either partial processing
+        or full processing."""
+        for picking in self:
+            res = picking.do_new_transfer()
+            if res:
+                if not res.get('res_model') or not res.get('res_id'):
+                    continue
+                wizard = self.env[res.get('res_model')].browse(
+                    res.get('res_id'))
+                wizard.process()
+            else:
+                continue
+        return