Always create or update autosave

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

@@ -362,25 +362,6 @@ public function create_post_autosave( $post_data ) {
 			$new_autosave['ID']          = $old_autosave->ID;
 			$new_autosave['post_author'] = $user_id;
 
-			// If the new autosave has the same content as the post, delete the autosave.
-			$autosave_is_different = false;
-
-			foreach ( array_intersect( array_keys( $new_autosave ), array_keys( _wp_post_revision_fields( $post ) ) ) as $field ) {
-				if ( normalize_whitespace( $new_autosave[ $field ] ) !== normalize_whitespace( $post->$field ) ) {
-					$autosave_is_different = true;
-					break;
-				}
-			}
-
-			if ( ! $autosave_is_different ) {
-				wp_delete_post_revision( $old_autosave->ID );
-				return new WP_Error(
-					'rest_autosave_no_changes',
-					__( 'There is nothing to save. The autosave and the post content are the same.' ),
-					array( 'status' => 400 )
-				);
-			}
-
 			/** This filter is documented in wp-admin/post.php */
 			do_action( 'wp_creating_autosave', $new_autosave );