Taxonomy: Take 'parent' into account when checking for terms with duplicate names.

Terms with duplicate names are not allowed at the same level of a
taxonomy hierarchy. The name lookup introduced in [34809] did not
properly account for the 'parent' parameter, with the result that
the duplicate-name restriction was tighter than intended (terms
with duplicate names could not be created at different levels of
a single hierarchy).

Props mikejolley.
Fixes #39984.
Built from https://develop.svn.wordpress.org/trunk@40145


git-svn-id: http://core.svn.wordpress.org/trunk@40084 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/taxonomy.php

@@ -2040,6 +2040,7 @@ function wp_insert_term( $term, $taxonomy, $args = array() ) {
 	$name_matches = get_terms( $taxonomy, array(
 		'name' => $name,
 		'hide_empty' => false,
+		'parent' => $args['parent'],
 	) );
 
 	/*

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.8-alpha-40144';
+$wp_version = '4.8-alpha-40145';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.