Sorry, the email gateway of Roundup ate half of my snippets.
Here they are again:

>>> zlib.compress(u"ha")
'x\x9c\xcbH\x04\x00\x013\x00\xca'
>>> zlib.compress(u"hà")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
UnicodeEncodeError: 'ascii' codec can't encode character u'\xe0' in position 1: ordinal not in range(128)

>>> pwd.getpwnam(u"root")
pwd.struct_passwd(pw_name='root', pw_passwd='x', pw_uid=0, pw_gid=0, pw_gecos='root', pw_dir='/root', pw_shell='/bin/bash')
>>> pwd.getpwnam(u"rooté")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
UnicodeEncodeError: 'ascii' codec can't encode character u'\xe9' in position 4: ordinal not in range(128)