Update to Drupal 8.0.1. For more information, see https://www.drupal.org/node/2627402

core/lib/Drupal/Core/Routing/LinkGeneratorTrait.php

@@ -3,6 +3,9 @@
 /**
  * @file
  * Contains \Drupal\Core\Routing\LinkGeneratorTrait.
+ *
+ * @deprecated in Drupal 8.0.0 and will be removed before Drupal 9.0.0.
+ *   Use \Drupal\Core\Link instead.
  */
 
 namespace Drupal\Core\Routing;
@@ -37,6 +40,9 @@ trait LinkGeneratorTrait {
    * @return \Drupal\Core\GeneratedLink
    *   A GeneratedLink object containing a link to the given route and
    *   parameters and bubbleable metadata.
+   *
+   * @deprecated in Drupal 8.0.0 and will be removed before Drupal 9.0.0.
+   *   Use \Drupal\Core\Link instead.
    */
   protected function l($text, Url $url) {
     return $this->getLinkGenerator()->generate($text, $url);

core/lib/Drupal/Core/Routing/RouteProvider.php

@@ -257,7 +257,7 @@ class RouteProvider implements PreloadableRouteProviderInterface, PagedRouteProv
     if ($number_parts == 1) {
       $masks = array(1);
     }
-    elseif ($number_parts <= 3) {
+    elseif ($number_parts <= 3 && $number_parts > 0) {
       // Optimization - don't query the state system for short paths. This also
       // insulates against the state entry for masks going missing for common
       // user-facing paths since we generate all values without checking state.
@@ -272,7 +272,6 @@ class RouteProvider implements PreloadableRouteProviderInterface, PagedRouteProv
       $masks = (array) $this->state->get('routing.menu_masks.' . $this->tableName, array());
     }
 
-
     // Only examine patterns that actually exist as router items (the masks).
     foreach ($masks as $i) {
       if ($i > $end) {

core/lib/Drupal/Core/Routing/StackedRouteMatchInterface.php

@@ -33,7 +33,7 @@ interface StackedRouteMatchInterface extends RouteMatchInterface {
   /**
    * Returns the parent route match of the current.
    *
-   * @return \Drupal\Core\Routing\RouteMatchInterface\NULL
+   * @return \Drupal\Core\Routing\RouteMatchInterface|NULL
    *   The parent route match or NULL, if it the master route match.
    */
   public function getParentRouteMatch();

core/lib/Drupal/Core/Routing/UrlGeneratorTrait.php

@@ -3,6 +3,9 @@
 /**
  * @file
  * Contains \Drupal\Core\Routing\UrlGeneratorTrait.
+ *
+ * @deprecated in Drupal 8.0.0 and will be removed before Drupal 9.0.0.
+ *   Use \Drupal\Core\Url instead.
  */
 
 namespace Drupal\Core\Routing;
@@ -34,6 +37,9 @@ trait UrlGeneratorTrait {
    *
    * @return string
    *   The generated URL for the given route.
+   *
+   * @deprecated in Drupal 8.0.0 and will be removed before Drupal 9.0.0.
+   *   Use \Drupal\Core\Url instead.
    */
   protected function url($route_name, $route_parameters = array(), $options = array()) {
     return $this->getUrlGenerator()->generateFromRoute($route_name, $route_parameters, $options);

core/lib/Drupal/Core/Routing/routing.api.php

@@ -43,7 +43,10 @@
  *   by the machine name of the module that defines the route, or the name of
  *   a subsystem.
  * - The 'path' line gives the URL path of the route (relative to the site's
- *   base URL).
+ *   base URL). Note: The path in Drupal is treated case insensitive so
+ *   /example and /EXAmplE should return the same page.
+ *   @todo Fix https://www.drupal.org/node/2075889 to actually get this
+ *   behaviour.
  * - The 'defaults' section tells how to build the main content of the route,
  *   and can also give other information, such as the page title and additional
  *   arguments for the route controller method. There are several possibilities