fix(web): issue2551356. Add etag header for not-modified (304) request. When a 304 is returned to a conditional request for a static file, print an ETag for the response. ETag was always sent with a 200 response. This also adds initial support for if-none-match conditional requests for static files. Changes: Refactors the if-modified-since code out to a method. It moves a file stat call from serve_static_file to _serve_file so that an etag can be generated by both serve_static_file and serve_file which call _serve_file. Tests added. This does not test the codepath where serve_file pulls content from the database rather than from a local file on disk. Test mocking _serve_file changed to account for 5th argument to serve_file BREAKING CHANGE: function signature for client.py-Client::_serve_file() now has 5 not 4 parameters (added etag param). Since this is a "hidden" method I am not too worried about it.

recursive-include share *
recursive-include roundup *.py *.txt
recursive-include frontends *.*
recursive-include scripts *.* *-*
recursive-include scripts/Docker Dockerfile *.* *_*
recursive-include tools *.* base64
recursive-include test *.py *.txt
include test/pg_service.conf
recursive-include doc *.html *.gif *.png *.txt *.css *.example
recursive-include detectors *.py README.txt
include demo.py *.txt
global-exclude *.pyc *.pyo .DS_Store *.orig *.rej *~ \#* .flake8
include doc/conf.py doc/Makefile doc/requirements.pip doc/roundup-favicon.ico
include doc/format_config.awk
include locale/*.po locale/*.mo locale/roundup.pot locale/Makefile