[web/headers] don't list a request header twice in "Vary"

[test] silence a few more deprecation warnings in unittest_hooks self.session → cnx.

[session] call rollback in Connection.__exit__ If we just free the cnxset and clear the Connection, we're missing the pending operation's rollback_event callbacks, which may be needed for cleanup.

[devtools] pre_setup_database takes a Connection, not a Session

[source/native] cPickle is available in all supported pythons

devtools: deprecate .req_from_url Which uses .request() And instead provide .admin_request_from_url, which is a context manager yielding the request.

[tests] Add a webtest based TestCase class Closes #4002134

[tests] Move 'anonymous_allowed' property from CubicWebServerTC to CubicWebTC The effective set of the property on the config is now done later that before, ie at the end of CubicWebTC.init_config instead of before. It is believed not to have an impact on the test suites that uses `anonymous_allowed`. Related to #4002134

[compat] Remove imports of "any" and "all" from lgc (closes #4306044) They're builtin since python 2.5.

[css] Remove the `div` tag specification of the pendingDelete css rule The HTML tag was changed by e2f96b16c3bd from a div to a span without changing the css rule accordingly. Closes #4285248.