Ticket #20733: 20733.patch.2

Index: wp-includes/class-wp-customize-manager.php
===================================================================
--- wp-includes/class-wp-customize-manager.php  (revision 20860)
+++ wp-includes/class-wp-customize-manager.php  (working copy)
@@ -514,8 +514,10 @@
                $ap = $a->priority;
                $bp = $b->priority;
 
-               if ( $ap == $bp )
-                       return 0;
+               if ( $ap == $bp ) {
+                       $section_keys = array_keys( $this->sections );
+                       return array_search( $a->id, $section_keys ) < array_search( $b->id, $section_keys );
+               }
                return ( $ap > $bp ) ? 1 : -1;
        }