Error while creating a quotation

If the sale_commission module is installed I get this error while chosing the partner:

Server Traceback (most recent call last):
File "/opt/openerp/openerp7/web/addons/web/session.py", line 90, in send
return openerp.netsvc.dispatch_rpc(service_name, method, args)
File "/opt/openerp/env/local/lib/python2.7/site-packages/openerp-7.0-py2.7.egg/openerp/netsvc.py", line 293, in dispatch_rpc
result = ExportService.getService(service_name).dispatch(method, params)
File "/opt/openerp/env/local/lib/python2.7/site-packages/openerp-7.0-py2.7.egg/openerp/service/web_services.py", line 626, in dispatch
res = fn(db, uid, *params)
File "/opt/openerp/env/local/lib/python2.7/site-packages/openerp-7.0-py2.7.egg/openerp/osv/osv.py", line 188, in execute_kw
return self.execute(db, uid, obj, method, *args, **kw or {})
File "/opt/openerp/env/local/lib/python2.7/site-packages/openerp-7.0-py2.7.egg/openerp/osv/osv.py", line 131, in wrapper
return f(self, dbname, *args, **kwargs)
File "/opt/openerp/env/local/lib/python2.7/site-packages/openerp-7.0-py2.7.egg/openerp/osv/osv.py", line 197, in execute
res = self.execute_cr(cr, uid, obj, method, *args, **kw)
File "/opt/openerp/openerp7/addons/audittrail/audittrail.py", line 514, in execute_cr
return fct_src(cr, uid, model, method, *args, **kw)
File "/opt/openerp/env/local/lib/python2.7/site-packages/openerp-7.0-py2.7.egg/openerp/osv/osv.py", line 185, in execute_cr
return getattr(object, method)(cr, uid, *args, **kw)
File "/opt/openerp/openerp7/addons/delivery/sale.py", line 34, in onchange_partner_id
result = super(sale_order, self).onchange_partner_id(cr, uid, ids, part, context=context)
TypeError: onchange_partner_id() got an unexpected keyword argument 'context'

Env: OpenERP 7