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.

# copied from nosyreaction

from roundup import roundupdb

def newissuecopy(db, cl, nodeid, oldvalues):
    ''' Copy a message about new issues to a team address.
    '''
    # get relevant crypto settings
    encrypt = db.config.PGP_ENABLE and db.config.PGP_ENCRYPT

    # so use all the messages in the create
    change_note = cl.generateCreateNote(nodeid)

    # send a copy to the nosy list
    for msgid in cl.get(nodeid, 'messages'):
        try:
            # note: fourth arg must be a list
            cl.send_message(nodeid, msgid, change_note,
                            ['team@team.host'],
                            crypt=encrypt)
        except roundupdb.MessageSendError as message:
            raise roundupdb.DetectorError(message)

def init(db):
    db.issue.react('create', newissuecopy)

# vim: set filetype=python ts=4 sw=4 et si