diff --git a/wp-includes/post-template.php b/wp-includes/post-template.php
index c058ed7a48..924e3996fb 100644
--- a/wp-includes/post-template.php
+++ b/wp-includes/post-template.php
@@ -398,15 +398,15 @@ function get_the_excerpt( $post = null ) {
 }
 
 /**
- * Whether post has excerpt.
+ * Whether the post has a custom excerpt.
  *
  * @since 2.3.0
  *
- * @param int|WP_Post $id Optional. Post ID or post object.
- * @return bool
+ * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global $post.
+ * @return bool True if the post has a custom excerpt, false otherwise.
  */
-function has_excerpt( $id = 0 ) {
-	$post = get_post( $id );
+function has_excerpt( $post = 0 ) {
+	$post = get_post( $post );
 	return ( !empty( $post->post_excerpt ) );
 }
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index cd804f0497..7961bfb3b7 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.8-alpha-40041';
+$wp_version = '4.8-alpha-40042';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.