询问的原因是由于 Flatpak 1.12.7 漏洞，尝试添加 Flatpak PPA 时系统超时。
sudo add-apt-repository ppa:flatpak/stable -y
[sudo] password for daniel:
Traceback (most recent call last):
File "/usr/bin/add-apt-repository", line 364, in <module>
sys.exit(0 if addaptrepo.main() else 1)
File "/usr/bin/add-apt-repository", line 347, in main
shortcut = handler(source, **shortcut_params)
File "/usr/lib/python3/dist-packages/softwareproperties/shortcuts.py", line 40, in shortcut_handler
return handler(shortcut, **kwargs)
File "/usr/lib/python3/dist-packages/softwareproperties/ppa.py", line 82, in __init__
if self.lpppa.publish_debug_symbols:
File "/usr/lib/python3/dist-packages/softwareproperties/ppa.py", line 120, in lpppa
self._lpppa = self.lpteam.getPPAByName(name=self.ppaname)
File "/usr/lib/python3/dist-packages/softwareproperties/ppa.py", line 107, in lpteam
self._lpteam = self.lp.people(self.teamname)
File "/usr/lib/python3/dist-packages/softwareproperties/ppa.py", line 98, in lp
self._lp = login_func("%s.%s" % (self.__module__, self.__class__.__name__),
File "/usr/lib/python3/dist-packages/launchpadlib/launchpad.py", line 494, in login_anonymously
return cls(
File "/usr/lib/python3/dist-packages/launchpadlib/launchpad.py", line 230, in __init__
super(Launchpad, self).__init__(
File "/usr/lib/python3/dist-packages/lazr/restfulclient/resource.py", line 472, in __init__
self._wadl = self._browser.get_wadl_application(self._root_uri)
File "/usr/lib/python3/dist-packages/lazr/restfulclient/_browser.py", line 447, in get_wadl_application
response, content = self._request(url, media_type=wadl_type)
File "/usr/lib/python3/dist-packages/lazr/restfulclient/_browser.py", line 389, in _request
response, content = self._request_and_retry(
File "/usr/lib/python3/dist-packages/lazr/restfulclient/_browser.py", line 359, in _request_and_retry
response, content = self._connection.request(
File "/usr/lib/python3/dist-packages/httplib2/__init__.py", line 1725, in request
(response, content) = self._request(
File "/usr/lib/python3/dist-packages/launchpadlib/launchpad.py", line 144, in _request
response, content = super(LaunchpadOAuthAwareHttp, self)._request(
File "/usr/lib/python3/dist-packages/lazr/restfulclient/_browser.py", line 184, in _request
return super(RestfulHttp, self)._request(
File "/usr/lib/python3/dist-packages/httplib2/__init__.py", line 1441, in _request
(response, content) = self._conn_request(conn, request_uri, method, body, headers)
File "/usr/lib/python3/dist-packages/httplib2/__init__.py", line 1363, in _conn_request
conn.connect()
File "/usr/lib/python3/dist-packages/httplib2/__init__.py", line 1153, in connect
sock.connect((self.host, self.port))
TimeoutError: [Errno 110] Connection timed out