[web] fix headers on 304 responses (closes #11466875)
The response MUST include the following header fields:
[...]
- ETag and/or Content-Location, if the header would have been sent
in a 200 response to the same request
https://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.3.5
Unfortunately we weren't copying headers from what would have been the
200 response, but from the request.
.. _web_module:
:mod:`cubicweb.web`
===================
.. automodule:: cubicweb.web
Exceptions
----------
.. autoexception:: DirectResponse
.. autoexception:: InvalidSession
.. autoexception:: PublishException
.. autoexception:: LogOut
.. autoexception:: Redirect
.. autoexception:: StatusResponse
.. autoexception:: RequestError
.. autoexception:: NothingToEdit
.. autoexception:: ProcessFormError
.. autoexception:: NotFound
.. autoexception:: RemoteCallFailed