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.

from roundup.mailgw import parseContent

def summarygenerator(db, cl, nodeid, newvalues):
    ''' If the message doesn't have a summary, make one for it.
    '''
    if 'summary' in newvalues or 'content' not in newvalues:
        return

    summary, content = parseContent(newvalues['content'], config=db.config)
    newvalues['summary'] = summary


def init(db):
    # fire before changes are made
    db.msg.audit('create', summarygenerator)

# vim: set filetype=python ts=4 sw=4 et si
#SHA: 538f90cb7f4eb63f77eca252b87afbe037d29c48