$> diff -c /usr/lib/python3.2/argparse.py argparse.py
*** /usr/lib/python3.2/argparse.py      2012-09-12 10:45:04.176893518 +0200
--- argparse.py 2012-09-12 10:44:58.383564516 +0200
***************
*** 1421,1427 ****
              if not dest:
                  msg = _('dest= is required for options like %r')
                  raise ValueError(msg % option_string)
!             dest = dest.replace('-', '_')

          # return the updated keyword arguments
          return dict(kwargs, dest=dest, option_strings=option_strings)
--- 1421,1428 ----
              if not dest:
                  msg = _('dest= is required for options like %r')
                  raise ValueError(msg % option_string)
!             # Replace non-alnum chars with underscores
!             dest = _re.sub(r'[^a-z0-9]', '_', dest, _re.IGNORECASE)

          # return the updated keyword arguments
          return dict(kwargs, dest=dest, option_strings=option_strings)