old_contents: # Amara, universalsubtitles.org
  #
  # Copyright (C) 2015 Participatory Culture Foundation
  #
  # This program is free software: you can redistribute it and/or modify
  # it under the terms of the GNU Affero General Public License as
  # published by the Free Software Foundation, either version 3 of the
  # License, or (at your option) any later version.
  #
  # This program is distributed in the hope that it will be useful,
  # but WITHOUT ANY WARRANTY; without even the implied warranty of
  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  # GNU Affero General Public License for more details.
  #
  # You should have received a copy of the GNU Affero General Public License
  # along with this program.  If not, see
  # http://www.gnu.org/licenses/agpl-3.0.html.
  
  from datetime import datetime
  
  def now():
      """Get the current datetime.
  
      This function is better to use than datetime.now() because it has support
      for mocking it up in unittests.
      """
      return datetime.now()
  
  def this_month_start():
      return month_start(now())
  
  def month_start(dt):
      """Get the first day of a month
  
      dt can be either datetime or date object, it will be converted to a date.
      """
      if isinstance(dt, datetime):
          dt = dt.date()
      return dt.replace(day=1)
  
  def inc_month(dt):
      if dt.month < 12:
          return dt.replace(month=dt.month+1)
      else:
          return dt.replace(year=dt.year+1, month=1)
  
  def dec_month(dt):
      if dt.month > 0:
          return dt.replace(month=dt.month-1)
      else:
          return dt.replace(year=dt.year-1, month=12)
  
new_contents: # Amara, universalsubtitles.org
  #
  # Copyright (C) 2015 Participatory Culture Foundation
  #
  # This program is free software: you can redistribute it and/or modify
  # it under the terms of the GNU Affero General Public License as
  # published by the Free Software Foundation, either version 3 of the
  # License, or (at your option) any later version.
  #
  # This program is distributed in the hope that it will be useful,
  # but WITHOUT ANY WARRANTY; without even the implied warranty of
  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  # GNU Affero General Public License for more details.
  #
  # You should have received a copy of the GNU Affero General Public License
  # along with this program.  If not, see
  # http://www.gnu.org/licenses/agpl-3.0.html.
  
  from datetime import datetime
  
  def now():
      """Get the current datetime.
  
      This function is better to use than datetime.now() because it has support
      for mocking it up in unittests.
      """
      return datetime.now()
  
  def this_month_start():
      return month_start(now())
  
  def month_start(dt):
      """Get the first day of a month
  
      dt can be either datetime or date object, it will be converted to a date.
      """
      if isinstance(dt, datetime):
          dt = dt.date()
      return dt.replace(day=1)
  
  def inc_month(dt):
      if dt.month < 12:
          return dt.replace(month=dt.month+1)
      else:
          return dt.replace(year=dt.year+1, month=1)
  
  def dec_month(dt):
      if dt.month > 1:
          return dt.replace(month=dt.month-1)
      else:
          return dt.replace(year=dt.year-1, month=12)
  
subject: Fix for dec_month()