-I

    Run Python in isolated mode. This also implies -E and -s. In isolated mode
    sys.path contains neither the script’s directory nor the user’s
    site-packages directory. All PYTHON* environment variables are ignored,
    too. Further restrictions may be imposed to prevent the user from
    injecting malicious code.

not to stderr.  Patch by Berker Peksag and Michael Dickens.

(test.regrtest and test.script_helper enable faulthandler module in
subprocesses).

#17323: The "[X refs, Y blocks]" printed by debug builds has been disabled by default.  It can be re-enabled with the `-X showrefcount` option.

TESTFN_NONASCII of test.support from Python 3.4. Backport tests on non-ASCII
paths.

#16306: Fix multiple error messages when unknown command line parameters where passed to the interpreter.  Patch by Hieu Nguyen.

#16306: Fix multiple error messages when unknown command line parameters where passed to the interpreter.  Patch by Hieu Nguyen.

Patch by Victor Stinner.

Patch by Victor Stinner.

These constants are used to test functions with non-ASCII data, especially
filenames.

  Patch by Alon Horev with update by Alexey Kachayev.

Thanks to Armin Rigo and Alexey Kachayev.

sys.stdout and sys.stderr are now using "\r\n" newline on Windows, as Python 2.

sys.stdout and sys.stderr are now using "\r\n" newline on Windows, as Python 2.

  environment variable, to provide an opt-in way to protect against denial of
  service attacks due to hash collisions within the dict and set types.  Patch
  by David Malcolm, based on work by Victor Stinner.

in order to make algorithmic complexity attacks on (e.g.) web apps much more complicated.

The environment variable PYTHONHASHSEED and the new command line flag -R control this
behavior.

It was already the case with Python 2.  However, the corresponding
sys module entries are now set to None (instead of an unusable file object).

Issue #13444: When stdout has been closed explicitly, we should not attempt to flush it at shutdown and print an error.

This also adds a test for issue #5319, whose resolution introduced the issue.

Patch by Francisco Martín Brugué.

'latin-1' and 'utf-8'.

These are optimized in the Python Unicode implementation
to result in more direct processing, bypassing the codec
registry.

Also see issue11303.

svn+ssh://pythondev@svn.python.org/python/branches/py3k

........
  r88530 | victor.stinner | 2011-02-23 13:07:37 +0100 (mer., 23 févr. 2011) | 4 lines

  Issue #11272: Fix input() and sys.stdin for Windows newline

  On Windows, input() strips '\r' (and not only '\n'), and sys.stdin uses
  universal newline (replace '\r\n' by '\n').
........

On Windows, input() strips '\r' (and not only '\n'), and sys.stdin uses
universal newline (replace '\r\n' by '\n').

UnicodeEncodeError.

svn+ssh://pythondev@svn.python.org/python/branches/py3k

........
  r86081 | brian.curtin | 2010-11-01 09:00:33 -0500 (Mon, 01 Nov 2010) | 2 lines

  Close subprocess pipes to clear ResourceWarning messages in debug mode.
........

They can be retrieved through a new attribute `sys._xoptions`.

the locale encoding. If the LANG (and LC_ALL and LC_CTYPE) environment variable
is not set, the locale encoding is ISO-8859-1, whereas most programs (including
Python) expect UTF-8. Python already uses UTF-8 for the filesystem encoding and
to encode command line arguments on this OS.