The documentation at http://docs.python.org/dev/library/argparse.html explicitly says that "If file is None, sys.stderr is assumed".

However, both print_usage and print_help assume sys.stdout when file=None. The helper method _print_message actually does it right, when called with file=None.

I think this is a documentation bug, since IMO help should print on stdout, not stderr[1].  I would expect print_usage to do likewise, but for the error to tell print_usage to write to stderr when it calls it...which is exactly what the code does.

[1] I know some unix commands print help to stderr, and this really annoys me when I pipe long help output to less....and it *still* scrolls off the screen.

Yep, this is a documentation bug. Help is definitely intended to print to stdout.

Fixed in r87372.

This apparently lacks a 2.7 backport.

Like Georg, I'll get to that when I do a mass backport of all my doc fixes.  My apologies for missing the beta2 deadline on doing that, but there aren't many of them.

Alright, I didn’t know you were doing mass merges.  I personally prefer to leave reports open until backported, now I’ll know your habits.

The version action currently writes to stderr. The _VersionAction(Action)'s __call__() method finishes off with 

parser.exit(message=formatter.format_help())

and parser.exit() by default writes to stderr.

Here, Steven says "Help is definitely intended to print to stdout." and I expected the same to happen regarding the version information. Why should it go to stderr?

I see that this is a minor problem and only if someone here agrees I would open an issue for that.