Ticket #47842: #47842.3

Index: wp-admin/includes/class-wp-debug-data.php
===================================================================
--- wp-admin/includes/class-wp-debug-data.php   (revision 45888)
+++ wp-admin/includes/class-wp-debug-data.php   (working copy)
@@ -42,6 +42,7 @@
                $core_version           = get_bloginfo( 'version' );
                $core_updates           = get_core_updates();
                $core_update_needed     = '';
+               $core_timezone                  = wp_timezone_string();
 
                foreach ( $core_updates as $core => $update ) {
                        if ( 'upgrade' === $update->response ) {
@@ -52,6 +53,10 @@
                        }
                }
 
+               if ( !get_option( 'timezone_string' ) ) {
+                       $core_timezone = 'UTC' . $core_timezone;
+               }
+
                // Set up the array that holds all debug information.
                $info = array();
 
@@ -106,6 +111,10 @@
                                        'value' => $is_multisite ? __( 'Yes' ) : __( 'No' ),
                                        'debug' => $is_multisite,
                                ),
+                               'core_timezone'                  => array(
+                                       'label' => __( 'Site Timezone' ),
+                                       'value' => $core_timezone,
+                               ),
                        ),
                );