old_contents: 
  from openerp import models, fields, api, _
  
  class res_currency_rate(models.Model):
      _inherit = 'res.currency.rate'
  
      @api.one
      @api.onchange('rate') # if these fields are changed, call method
      def check_change_rate(self):
          self.update_prices()
  
      @api.model
      def update_prices(self):
          #import pdb;pdb.set_trace();
          products = self.env['product.product'].search([])
          for product in products:
              if self.rate>0:
                  new_price = product.lst_price / self.rate
                  vals = {
                      'meli_price': str(new_price)
                      }
                  product.write(vals)
  
  
  res_currency_rate()
  
  
new_contents: 
  from openerp import models, fields, api, _
  
  class res_currency_rate(models.Model):
      _inherit = 'res.currency.rate'
  
      @api.one
      @api.onchange('rate') # if these fields are changed, call method
      def check_change_rate(self):
          self.update_prices()
  
      @api.model
      def update_prices(self):
          #import pdb;pdb.set_trace();
          products = self.env['product.product'].search([])
          for product in products:
              if self.rate>0 and not product.meli_price_fixed:
                  new_price = math.ceil( product.lst_price / self.rate )
                  vals = {
                      'meli_price': str(new_price)
                      }
                  product.write(vals)
  
  
  res_currency_rate()
  
  
subject: Fix ok! price ceiled