Issue #2846770 by diqidoq, dorian.dirusso, marie.pinet, Thib, larowlan,...

Issue #2846770 by diqidoq, dorian.dirusso, marie.pinet, Thib, larowlan, Mile23, andypost: AdminRouteSubscriber incorrectly identifies paths such as /administration-position as admin paths

(cherry picked from commit d7ab8310)

core/modules/system/src/EventSubscriber/AdminRouteSubscriber.php

@@ -17,7 +17,8 @@ class AdminRouteSubscriber extends RouteSubscriberBase {
    */
   protected function alterRoutes(RouteCollection $collection) {
     foreach ($collection->all() as $route) {
-      if (strpos($route->getPath(), '/admin') === 0 && !$route->hasOption('_admin_route') && static::isHtmlRoute($route)) {
+      $path = $route->getPath();
+      if (($path == '/admin' || strpos($path, '/admin/') === 0) && !$route->hasOption('_admin_route') && static::isHtmlRoute($route)) {
         $route->setOption('_admin_route', TRUE);
       }
     }

core/modules/system/tests/src/Unit/Routing/AdminRouteSubscriberTest.php

@@ -38,6 +38,27 @@ public function providerTestAlterRoutes() {
       new Route('/admin/foo'),
       TRUE,
     ];
+    $data['admin only'] = [
+      new Route('/admin'),
+      TRUE,
+    ];
+    $data['admin in part of a word'] = [
+      new Route('/administration/foo'),
+      NULL,
+    ];
+    $data['admin in part of a word with admin_route option'] = [
+      (new Route('/administration/foo'))
+        ->setOption('_admin_route', TRUE),
+      TRUE,
+    ];
+    $data['admin not at the start of the path'] = [
+      new Route('/foo/admin/bar'),
+      NULL,
+    ];
+    $data['admin in part of a word not at the start of the path'] = [
+      new Route('/foo/administration/bar'),
+      NULL,
+    ];
     $data['admin option'] = [
       (new Route('/foo'))
         ->setOption('_admin_route', TRUE),