5.4.1でパーマリンクの仕様が一部変更された件

// Check post status to determine if post should be displayed.
if ( ! empty( $this->posts ) && ( $this->is_single || $this->is_page ) ) {
	$status = get_post_status( $this->posts[0] );

	if ( 'attachment' === $this->posts[0]->post_type && 0 === (int) $this->posts[0]->post_parent ) {
		$this->is_page       = false;
		$this->is_single     = true;
		$this->is_attachment = true;
	}

	// If the post_status was specifically requested, let it pass through.
	if ( ! in_array( $status, $q_status ) ) {
		$post_status_obj = get_post_status_object( $status );

		if ( $post_status_obj && ! $post_status_obj->public ) {
			if ( ! is_user_logged_in() ) {
				// User must be logged in to view unpublished posts.
				$this->posts = array();
			} else {
				if ( $post_status_obj->protected ) {
					// User must have edit permissions on the draft to preview.
					if ( ! current_user_can( $edit_cap, $this->posts[0]->ID ) ) {
						$this->posts = array();
					} else {
						$this->is_preview = true;
						if ( 'future' != $status ) {
							$this->posts[0]->post_date = current_time( 'mysql' );
						}
					}
				} elseif ( $post_status_obj->private ) {
					if ( ! current_user_can( $read_cap, $this->posts[0]->ID ) ) {
						$this->posts = array();
					}
				} else {
					$this->posts = array();
				}
			}
		} elseif ( ! $post_status_obj ) {
			// Post status is not registered, assume it's not public.
			if ( ! current_user_can( $edit_cap, $this->posts[0]->ID ) ) {
				$this->posts = array();
			}
		}
	}

	if ( $this->is_preview && $this->posts && current_user_can( $edit_cap, $this->posts[0]->ID ) ) {
		/**
		 * Filters the single post for preview mode.
		 *
		 * @since 2.7.0
		 *
		 * @param WP_Post  $post_preview  The Post object.
		 * @param WP_Query $this          The WP_Query instance (passed by reference).
		 */
		$this->posts[0] = get_post( apply_filters_ref_array( 'the_preview', array( $this->posts[0], &$this ) ) );
	}
}