Customize: Correct docs for WP_Customize_Manager::changeset_uuid() after changes in [41626].

Props dlh.
Fixes #42174.

Built from https://develop.svn.wordpress.org/trunk@41825


git-svn-id: http://core.svn.wordpress.org/trunk@41659 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-wp-customize-manager.php

@@ -788,10 +788,8 @@ final class WP_Customize_Manager {
 	 * Get the changeset UUID.
 	 *
 	 * @since 4.7.0
-	 * @since 4.9.0 An exception is thrown if the changeset UUID has not been established yet.
 	 * @see WP_Customize_Manager::establish_loaded_changeset()
 	 *
-	 * @throws Exception When the UUID has not been set yet.
 	 * @return string UUID.
 	 */
 	public function changeset_uuid() {