bug symfony#20218 [HttpFoundation] no 304 response if method is not cacheable (xabbuh)

This PR was merged into the 2.7 branch.

Discussion
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[HttpFoundation] no 304 response if method is not cacheable

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

Since symfony#19321 OPTIONS and TRACE are considered safe methods. But both methods should not lead to "304 Not modified" responses.

Commits
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3d6b450 no 304 response if method is not cacheable

Author: fabpot

src/Symfony/Component/HttpFoundation/Response.php

@@ -1000,7 +1000,7 @@ public function setVary($headers, $replace = true)
      */
     public function isNotModified(Request $request)
     {
-        if (!$request->isMethodSafe()) {
+        if (!$request->isMethodCacheable()) {
             return false;
         }