Error when doing "make picking" : "Bad context propagation"

[Alexis de Lattre]

When an up-to-date server-trunk, addons-trunk and web-trunk, using the web client :

1. Create a new Purchase order with one purchase order line.
2. Click on "Confirm quotation"
3. Click on "Receive products"
4. Click on "Confirm and transfer"
-> you get the crash :

2012-07-09 16:56:27,711 13756 ERROR None openerp.osv.osv: Uncaught exception
Traceback (most recent call last):
  File "/home/alexis/new_boite/dev/server-trunk/openerp/osv/osv.py", line 121, in wrapper
    return f(self, dbname, *args, **kwargs)
  File "/home/alexis/new_boite/dev/server-trunk/openerp/osv/osv.py", line 176, in execute
    res = self.execute_cr(cr, uid, obj, method, *args, **kw)
  File "/home/alexis/new_boite/dev/server-trunk/openerp/osv/osv.py", line 164, in execute_cr
    return getattr(object, method)(cr, uid, *args, **kw)
  File "/home/alexis/new_boite/dev/addons-trunk/stock/wizard/stock_partial_picking.py", line 108, in default_get
    assert context.get('active_model') in ('stock.picking', 'stock.picking.in', 'stock.picking.out'), 'Bad context propagation'
AssertionError: Bad context propagation

In fact, context['active_model'] = 'purchase.order'... but, in the code, it is expected to have 'stock.picking', 'stock.picking.in' and 'stock.picking.out'.