id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
26765	Etags should not be added when no-store is used	Kevin Christopher Henry	nobody	"Glancing at the source code, it looks like `CommonMiddleware` (with `USE_ETAGS = True`) adds an Etag whenever there isn't one already.

However, according to [[https://tools.ietf.org/html/rfc7234|RFC 7234]], ""the ''no-store'' response directive indicates that a cache MUST NOT store any part of either the immediate request or response."" Since the response must not be stored, no compliant cache will be able to issue a conditional request, so computing the Etag is wasted effort. (Note that this behavior is different from ''no-cache''.)

The current behavior doesn't do any real harm, but we might as well improve the performance of such requests given that the change should be relatively easy (simply checking the header value)."	Cleanup/optimization	closed	HTTP handling	dev	Normal	fixed			Ready for checkin	1	0	0	0	0	0