feature #3883 Removed redundant POST request exclusion info (ryancastle)

This PR was submitted for the 2.4 branch but it was merged into the 2.3 branch instead (closes #3883).

Discussion
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Removed redundant POST request exclusion info

The default ``ExceptionListener::setTargetPath()`` already excludes POSTs/PUTs, so suggesting that people should implement their own listener to do this is a bit misleading.

However, doing this to prevent XMLHttpRequest URIs from being saved is still valuable.

Commits
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01fc656 Added comma after "For example"
c633f6b Improved clarity of explanation around overriding setTargetPath()
556365b Removed redundant POST request exclusion info

Author: weaverryan

cookbook/security/target_path.rst

@@ -10,9 +10,9 @@ the name of the firewall, defined in ``security.yml``). Upon a successful
 login, the user is redirected to this path, as to help them continue from the
 last known page they visited.
 
-On some occasions, this is unexpected. For example when the last request
-URI was an HTTP POST against a route which is configured to allow only a POST
-method, the user is redirected to this route only to get a 404 error.
+In some situations, this is not ideal. For example, when the last request
+URI was an XMLHttpRequest which returned a non-HTML or partial HTML response,
+the user is redirected back to a page which the browser cannot render.
 
 To get around this behavior, you would simply need to extend the ``ExceptionListener``
 class and override the default method named ``setTargetPath()``.
@@ -56,9 +56,10 @@ Next, create your own ``ExceptionListener``::
     {
         protected function setTargetPath(Request $request)
         {
-            // Do not save target path for XHR and non-GET requests
+            // Do not save target path for XHR requests
             // You can add any more logic here you want
-            if ($request->isXmlHttpRequest() || 'GET' !== $request->getMethod()) {
+            // Note that non-GET requests are already ignored
+            if ($request->isXmlHttpRequest()) {
                 return;
             }