old_contents: # -*- coding: utf-8 -*-
  # See README.rst file on addon root folder for license details
  
  from openerp import models, api
  from datetime import datetime, timedelta
  
  
  class ResourceCalendar(models.Model):
      _inherit = 'resource.calendar'
  
      @api.v7
      def get_working_days_of_date(self, cr, uid, id, start_dt=None, end_dt=None,
                                   leaves=None, compute_leaves=False,
                                   resource_id=None, default_interval=None,
                                   context=None):
          if start_dt is None:
              start_dt = datetime.now().replace(hour=0, minute=0, second=0)
          if end_dt is None:
              end_dt = datetime.now().replace(hour=23, minute=59, second=59)
          days = 0
          current = start_dt
          while current <= end_dt:
              if id is None:
                  days += 1
              else:
                  end_day = current.replace(hour=23, minute=59, second=59)
                  end = end_dt if end_day > end_dt else end_day
                  working_intervals = self.get_working_intervals_of_day(
                      cr, uid, id, start_dt=current, end_dt=end, leaves=leaves,
                      compute_leaves=compute_leaves, resource_id=resource_id,
                      default_interval=default_interval, context=context)
                  if working_intervals:
                      days += 1
              next = current + timedelta(days=1)
              current = next
          return days
  
new_contents: # -*- coding: utf-8 -*-
  # See README.rst file on addon root folder for license details
  
  from openerp import models, api
  from datetime import datetime, timedelta
  
  
  class ResourceCalendar(models.Model):
      _inherit = 'resource.calendar'
  
      @api.v7
      def get_working_days_of_date(self, cr, uid, id, start_dt=None, end_dt=None,
                                   leaves=None, compute_leaves=False,
                                   resource_id=None, default_interval=None,
                                   context=None):
          context = context or {}
          context['tz'] = 'UTC'
          if start_dt is None:
              start_dt = datetime.now().replace(hour=0, minute=0, second=0)
          if end_dt is None:
              end_dt = datetime.now().replace(hour=23, minute=59, second=59)
          days = 0
          current = start_dt
          while current <= end_dt:
              if id is None:
                  days += 1
              else:
                  end_day = current.replace(hour=23, minute=59, second=59)
                  end = end_dt if end_day > end_dt else end_day
                  working_intervals = self.get_working_intervals_of_day(
                      cr, uid, id, start_dt=current, end_dt=end, leaves=leaves,
                      compute_leaves=compute_leaves, resource_id=resource_id,
                      default_interval=default_interval, context=context)
                  if working_intervals:
                      days += 1
              next = current + timedelta(days=1)
              current = next
          return days
  
subject: Define UTC as tz in get_working_days_of_date method