Error when changing task stage from kanban view

[Yajo]

1. Add a task to a project. The task does not need to have dependencies, just the module installed.
2. Go to the projcet's kanban view.
3. Drag the task to another stage.
4. Error:

Client Traceback (most recent call last):
  File "/usr/lib/pymodules/python2.7/openerp/addons/web/http.py", line 204, in dispatch
    response["result"] = method(self, **self.params)
  File "/usr/lib/pymodules/python2.7/openerp/addons/web/controllers/main.py", line 1161, in resequence
    m.write(id, { field: i + offset })
  File "/usr/lib/pymodules/python2.7/openerp/addons/web/session.py", line 42, in proxy
    result = self.proxy.execute_kw(self.session._db, self.session._uid, self.session._password, self.model, method, args, kw)
  File "/usr/lib/pymodules/python2.7/openerp/addons/web/session.py", line 30, in proxy_method
    result = self.session.send(self.service_name, method, *args)
  File "/usr/lib/pymodules/python2.7/openerp/addons/web/session.py", line 103, in send
    raise xmlrpclib.Fault(openerp.tools.ustr(e), formatted_info)

Server Traceback (most recent call last):
  File "/usr/lib/pymodules/python2.7/openerp/addons/web/session.py", line 89, in send
    return openerp.netsvc.dispatch_rpc(service_name, method, args)
  File "/usr/lib/pymodules/python2.7/openerp/netsvc.py", line 292, in dispatch_rpc
    result = ExportService.getService(service_name).dispatch(method, params)
  File "/usr/lib/pymodules/python2.7/openerp/service/web_services.py", line 626, in dispatch
    res = fn(db, uid, *params)
  File "/usr/lib/pymodules/python2.7/openerp/osv/osv.py", line 190, in execute_kw
    return self.execute(db, uid, obj, method, *args, **kw or {})
  File "/usr/lib/pymodules/python2.7/openerp/osv/osv.py", line 132, in wrapper
    return f(self, dbname, *args, **kwargs)
  File "/usr/lib/pymodules/python2.7/openerp/osv/osv.py", line 199, in execute
    res = self.execute_cr(cr, uid, obj, method, *args, **kw)
  File "/usr/lib/pymodules/python2.7/openerp/osv/osv.py", line 187, in execute_cr
    return getattr(object, method)(cr, uid, *args, **kw)
  File "/opt/openerp-community-repo-installer/addons/project_task_dependencies/project.py", line 203, in write
    self.compute_earliest_start_successors(cr, uid, ids, context)
  File "/opt/openerp-community-repo-installer/addons/project_task_dependencies/project.py", line 159, in compute_earliest_start_successors
    for task in self.browse(cr, uid, ids, context=context):
  File "/usr/lib/pymodules/python2.7/openerp/osv/orm.py", line 505, in __iter__
    raise NotImplementedError("Iteration is not allowed on %s" % self)
NotImplementedError: Iteration is not allowed on browse_record(project.task, 50)

[Ferdinand (office-chricar)]

fix commited