analytic_user_function KeyError: 'amount'

It seems the module analytic_user_function is not working as expected in the 6.0 branch.

module: analytic_user_function
branch: http://bazaar.launchpad.net/~openerp/openobject-addons/6.0/
revno: 4543

steps to reproduce:
- install modules analytic_user_function and account_analytic_plans with demo data
- open analytic account "OpenERP Integration"
- in tab Users/Products Rel, add a line (User=Fabian, Product=Service on Timesheet)
- create a timesheet for user Fabian
- add a timesheet line
- in the new timesheet line select Analytic Account "OpenERP Integration"
- tab to next field and you get the stack trace below

Environment Information :
System : Linux-2.6.35-28-generic-i686-with-Ubuntu-10.10-maverick
OS Name : posix
LSB Version: core-2.0-ia32:core-2.0-noarch:core-3.0-ia32:core-3.0-noarch:core-3.1-ia32:core-3.1-noarch:core-3.2-ia32:core-3.2-noarch:core-4.0-ia32:core-4.0-noarch
Distributor ID: Ubuntu
Description: Ubuntu 10.10
Release: 10.10
Codename: maverick
Operating System Release : 2.6.35-28-generic
Operating System Version : #50-Ubuntu SMP Fri Mar 18 19:00:26 UTC 2011
Operating System Architecture : 32bit
Operating System Locale : fr_BE.UTF8
Python Version : 2.6.6
OpenERP-Client Version : 6.0.2
Last revision No. & ID :Bazaar Package not Found !Traceback (most recent call last):
  File "/home/stephane/Build/openerp6-python/lib/python2.6/site-packages/openerp-server/netsvc.py", line 489, in dispatch
    result = ExportService.getService(service_name).dispatch(method, auth, params)
  File "/home/stephane/Build/openerp6-python/lib/python2.6/site-packages/openerp-server/service/web_services.py", line 599, in dispatch
    res = fn(db, uid, *params)
  File "/home/stephane/Build/openerp6-python/lib/python2.6/site-packages/openerp-server/osv/osv.py", line 122, in wrapper
    return f(self, dbname, *args, **kwargs)
  File "/home/stephane/Build/openerp6-python/lib/python2.6/site-packages/openerp-server/osv/osv.py", line 176, in execute
    res = self.execute_cr(cr, uid, obj, method, *args, **kw)
  File "/home/stephane/Build/openerp6-python/lib/python2.6/site-packages/openerp-server/osv/osv.py", line 167, in execute_cr
    return getattr(object, method)(cr, uid, *args, **kw)
  File "/home/stephane/Build/openerp6/addons/analytic_user_function/analytic_user_function.py", line 102, in on_change_account_id
    r.product_id.id, unit_amount, False, r.product_id.uom_id.id)['value']['amount']
KeyError: 'amount'