Issue #2640650 by jibran, IRuslan: Update the version number from 8.0.x to 8.1.x

core/lib/Drupal.php

@@ -81,7 +81,7 @@ class Drupal {
   /**
    * The current system version.
    */
-  const VERSION = '8.0.0-dev';
+  const VERSION = '8.1.0-dev';
 
   /**
    * Core API compatibility.

core/modules/update/src/Tests/UpdateCoreTest.php

@@ -176,7 +176,7 @@ function testDatestampMismatch() {
     $system_info = array(
       '#all' => array(
         // We need to think we're running a -dev snapshot to see dates.
-        'version' => '8.0.0-dev',
+        'version' => '8.1.0-dev',
         'datestamp' => time(),
       ),
       'block' => array(