A common problem encountered when using python3 is writing non-ascii to stdout.  This will work fine if stdout is a terminal and the terminal encoding handles the characters, but will fail if stdout is later redirected to a pipe.  The docs for sys.stdout and for print should contain or point to an explanation of why, and how to solve the problem (ie: how to set the encoding for sys.stdout/sys.stderr).

Note that IMO it makes more sense for sys.stdout to default to the LOCALE encoding, but that should be a separate issue.