Index: src/wp-includes/nav-menu.php
===================================================================
--- src/wp-includes/nav-menu.php	(revision 45654)
+++ src/wp-includes/nav-menu.php	(working copy)
@@ -488,6 +488,12 @@
 		if ( '' == $args['menu-item-title'] && '' == $args['menu-item-description'] ) {
 			$args['menu-item-description'] = ' ';
 		}
+	} else {
+		/* if custom menu item, then:
+			* trim the original object's URL
+		 */
+
+		$args[ 'menu-item-url' ] = trim( $args[ 'menu-item-url' ] );
 	}
 
 	// Populate the menu item object