Ticket #55659: 55659.diff

src/wp-includes/rest-api/endpoints/class-wp-rest-autosaves-controller.php

@@ -220 +220 @@
                 $prepared_post->ID = $post->ID;
                 $user_id           = get_current_user_id();
 
-                if ( ( 'draft' === $post->post_status || 'auto-draft' === $post->post_status ) && $post->post_author == $user_id ) {
-                        // Draft posts for the same author: autosaving updates the post and does not create a revision.
+                /**
+                 * Auto save updates the original post when the
+                 * 1. post status is draft or auto-draft
+                 * 2. post author is the current logged in user
+                 * 3. current user holds the post lock
+                 */
+                if ( ( 'draft' === $post->post_status || 'auto-draft' === $post->post_status ) && $post->post_author == $user_id && false === wp_check_post_lock( $post->ID ) ) {
                         // Convert the post object to an array and add slashes, wp_update_post() expects escaped array.
                         $autosave_id = wp_update_post( wp_slash( (array) $prepared_post ), true );
                 } else {