[FIX] pyeval: be more fault tolerant to avoid wrap null values
[FIX] pyeval: be more fault tolerant to avoid wrap null values

havt/openerp-web,akretion/openerp-web,akretion/openerp-web,akretion/openerp-web,havt/openerp-web,havt/openerp-web,havt/openerp-web,havt/openerp-web