AssertionError when hostname contains spaces and characters outside of [a-z0-9-]

[Roman Yepishev]

First of all, no, you should never set your hostname to something that contains spaces, letters outsize of the ASCII space, special characters or minus sign. This is RFC 952 and 1123. It is technically possible to do this, but it does not make it a good idea.

Anyway...

If a hostname contains e.g. a space character, Ubuntu SSO backend will fail with AssertionError with the following in the log:

2012-11-28 19:59:05,047:47.0008850098 - ubuntu_sso.credentials - ERROR - find_credentials (app_name: Ubuntu Software Center): Problem while getting credentials from the keyring.
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/ubuntu-sso-client/ubuntu_sso/credentials.py", line 104, in inner
    result = yield f(self, *a, **kw)
AssertionError

This happens because the code in ubuntu_sso/keyring/__init__.py uses urllib.quote on the hostname previously converted to unicode. While there should be no real reason for the quoting anyway, this exposes a bug in quote() which does the following:

quote(u"normal-hostname") -> u"normal-hostname"
quote(u"broken hostname") -> 'broken%20hostname'

Afterwards assert(quoted_hostname, unicode) breaks and raises the exception.