Taxonomy: Avoid duplicates when querying for terms in taxonomies registered with `$args` parameter.

[40514] introduced a bug that caused term queries to return some duplicates
when the `$taxonomies` array contained only taxonomies that were originally
registered with an `$args` array. We fix this bug by ensuring that
recursive `get_terms()` queries stop when all queried `$taxonomies` have
already been referenced.

Props bor0, atanasangelovdev.
Fixes #41010.
Built from https://develop.svn.wordpress.org/trunk@41037


git-svn-id: http://core.svn.wordpress.org/trunk@40887 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/taxonomy.php

@@ -1917,7 +1917,10 @@ function wp_get_object_terms($object_ids, $taxonomies, $args = array()) {
 	$args['taxonomy'] = $taxonomies;
 	$args['object_ids'] = $object_ids;
 
-	$terms = array_merge( $terms, get_terms( $args ) );
+	// Taxonomies registered without an 'args' param are handled here.
+	if ( ! empty( $taxonomies ) ) {
+		$terms = array_merge( $terms, get_terms( $args ) );
+	}
 
 	/**
 	 * Filters the terms for a given object or objects.

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9-alpha-41036';
+$wp_version = '4.9-alpha-41037';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.