[tryton] Wrong SQL for update of product_template (postgresql) trytond 2.4

[Matthias Kracke]

Hi,

I extended for a customer the product_template. Now I want to save all 
changes made by the user. Here is my setup:

SaleLine extension:

    customs_tariff_number = fields.Char('Customs Tariff No.',
                                 states={
                                'invisible': Eval('type') != 'line'},
                                 on_change=['customs_tariff_number', 
'product'],
                                 depends=['type']
                                )

    def on_change_customs_tariff_number(self, vals):
        product_obj = Pool().get('product.product')
        product_id = vals.get('product')
        if product_id:
            product = product_obj.browse(product_id)
            p_template = product.template 
            p_template.write(p_template.id, {
                'customs_tariff_number': vals.get('customs_tariff_number')
                })

        return vals

and the product template:

    customs_tariff_number = fields.Char('Customs Tariff No.')

All I get is:

sql:Wrong SQL: UPDATE "product_template" SET "customs_tariff_number" = 
'986543',write_uid = 1,write_date = '2013-03-28T12:02:54.181374'::timestamp 
WHERE ((id IN (1)))

The error occurs in trytond/backend/postgresql/database.py for:

res = self.cursor.execute(sql, params)

with:
(Pdb) sql
'UPDATE "product_template" SET "customs_tariff_number" = %s,write_uid = 
%s,write_date = %s WHERE ((id IN (%s)))'
(Pdb) params
[u'986543', 1, datetime.datetime(2013, 3, 28, 12, 2, 54, 181374), 1]

Funny thing is, if I try the sql statement in pgAdmin3 everything works 
like expected.

Where is my mistake? What should I check?

I hope someone can help me,
Matthias Kracke