Accentuated characters are not accepted in password.
While it (unicode) was quickly talked about in issue557704 it appears that issue1170 aimed to solve this by making shlex unicode-compatible but it does not seem to be the case (at least with python 3.2 in the netrc use-case).

On a side note :
- a blank line between two comment lines
 and
- lines starting with a '#' *not* followed by a space
 fail too (shells supports both of them)

Do you have a small script to reproduce the issue?

$ python -c "import netrc; print netrc.netrc('/dev/stdin').authenticators('a')"<<<"machine a login b password c"
('b', None, 'c')

$ python -c "import netrc; print netrc.netrc('/dev/stdin').authenticators('a')"<<<"machine a login b password héhé"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib/python2.7/netrc.py", line 32, in __init__
    self._parse(file, fp)
  File "/usr/lib/python2.7/netrc.py", line 94, in _parse
    file, lexer.lineno)
netrc.NetrcParseError: bad follower token '\xc3' (/dev/stdin, line 1)

This is presumably going to turn out to be a problem with shlex's handling of non-ascii characters.  I believe there are open issues about that, but I'm not sure of the status.

I opened #28806 to improve netrc library. This could be solved if it's merged.

Now that a PR has landed in #28806 to improve shlex, we need to check whether this issue can/needs to move forward.