Customize: Fix reliability of just-in-time publishing for changesets that miss their schedule when visiting `customize.php`.

When just doing `wp_publish_post()` for the changeset from `customize.php`, any option-based settings will fail to get saved because `WP_Customize_Manager` would have already been loaded with `settings_previewed`, resulting in `update_option()` calls being short-circuited. So an admin-ajax request to `customize_save` is used to work around this.

Props westonruter, jeremyfelt, dlh for testing, LittleBigThing for testing.
Amends [41626].
See #28721, #39221.
Fixes #42457 for trunk.

Built from https://develop.svn.wordpress.org/trunk@42138


git-svn-id: http://core.svn.wordpress.org/trunk@41969 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/customize.php

@@ -42,10 +42,34 @@ if ( $wp_customize->changeset_post_id() ) {
 		get_post_time( 'G', true, $changeset_post ) < time()
 	);
 	if ( $missed_schedule ) {
-		wp_publish_post( $changeset_post->ID );
+		/*
+		 * Note that an Ajax request spawns here instead of just calling `wp_publish_post( $changeset_post->ID )`.
+		 *
+		 * Because WP_Customize_Manager is not instantiated for customize.php with the `settings_previewed=false`
+		 * argument, settings cannot be reliably saved. Some logic short-circuits if the current value is the
+		 * same as the value being saved. This is particularly true for options via `update_option()`.
+		 *
+		 * By opening an Ajax request, this is avoided and the changeset is published. See #39221.
+		 */
+		$nonces = $wp_customize->get_nonces();
+		$request_args = array(
+			'nonce' => $nonces['save'],
+			'customize_changeset_uuid' => $wp_customize->changeset_uuid(),
+			'wp_customize' => 'on',
+			'customize_changeset_status' => 'publish',
+		);
+		ob_start();
+		?>
+		<?php wp_print_scripts( array( 'wp-util' ) ); ?>
+		<script>
+			wp.ajax.post( 'customize_save', <?php echo wp_json_encode( $request_args ); ?> );
+		</script>
+		<?php
+		$script = ob_get_clean();
+
 		wp_die(
 			'<h1>' . __( 'Your scheduled changes just published' ) . '</h1>' .
-			'<p><a href="' . esc_url( remove_query_arg( 'changeset_uuid' ) ) . '">' . __( 'Customize New Changes' ) . '</a></p>',
+			'<p><a href="' . esc_url( remove_query_arg( 'changeset_uuid' ) ) . '">' . __( 'Customize New Changes' ) . '</a></p>' . $script,
 			200
 		);
 	}

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.0-alpha-42136';
+$wp_version = '5.0-alpha-42138';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.