When doctest.py is ran without arguments, it runs its
own docs
through itself and crashes with:

bagira:~/python/dist/src/Lib> ../python doctest1.121.py
...............F
======================================================================
FAIL: Doctest: __main__.set_unittest_reportflags
----------------------------------------------------------------------
Traceback (most recent call last):
  File "doctest1.121.py", line 2152, in runTest
    raise
self.failureException(self.format_failure(new.getvalue()))
AssertionError: Failed doctest test for
__main__.set_unittest_reportflags
  File "doctest1.121.py", line 2068, in
set_unittest_reportflags

----------------------------------------------------------------------
File "doctest1.121.py", line 2080, in
__main__.set_unittest_reportflags
Failed example:
    doctest._unittest_reportflags == (REPORT_NDIFF |
                                     
REPORT_ONLY_FIRST_FAILURE)
Expected:
    True
Got:
    False


----------------------------------------------------------------------
Ran 16 tests in 0.080s

FAILED (failures=1)

----------------------------------------------------------------------

The attached patch fixes the problem...