core, mod_rewrite: introduce the 'redirect-keeps-vary' note to allow proper Vary header insertion when …
core, mod_rewrite: introduce the 'redirect-keeps-vary' note to allow proper Vary header insertion when dealing with a RewriteRule in a directory context.This change is an attempt to fix a long standing problem,brought up while working on PR 58231. Our documentation clearlystates the following:"If a HTTP header is used in a condition this header is addedto the Vary header of the response in case the conditionevaluates to true for the request."This is currently not true for RewriteCond/Rules working ina directory context, since when an internal redirect happensall the outstanding response headers get dropped.There might be a better solution so I am looking forward tohear more opinions and comments. My goal for a delicate changelike this one would be to affect the least amount of configurationspossible, without triggering unwanted side effects.If the solution is good for everybody tests will be writtenin the suite asap.