Docs: Update the return description for `get_preview_post_link()` to note that it can also return null.

Props chris_dev, swissspidy.
See #35915.

Built from https://develop.svn.wordpress.org/trunk@37564


git-svn-id: http://core.svn.wordpress.org/trunk@37532 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/link-template.php

@@ -1210,7 +1210,7 @@ function get_post_type_archive_feed_link( $post_type, $feed = '' ) {
 /**
  * Retrieves the URL used for the post preview.
  *
- * Get the preview post URL. Allows additional query args to be appended.
+ * Allows additional query args to be appended.
  *
  * @since 4.4.0
  *
@@ -1219,7 +1219,7 @@ function get_post_type_archive_feed_link( $post_type, $feed = '' ) {
  *                                  Default empty array.
  * @param string      $preview_link Optional. Base preview link to be used if it should differ from the
  *                                  post permalink. Default empty.
- * @return string URL used for the post preview.
+ * @return string|null URL used for the post preview, or null if the post does not exist.
  */
 function get_preview_post_link( $post = null, $query_args = array(), $preview_link = '' ) {
 	$post = get_post( $post );

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.6-alpha-37563';
+$wp_version = '4.6-alpha-37564';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.