Index: wp-includes/shortcodes.php
===================================================================
--- wp-includes/shortcodes.php	(revision 6880)
+++ wp-includes/shortcodes.php	(working copy)
@@ -107,6 +107,8 @@
 			elseif (!empty($m[5]))
 				$atts[strtolower($m[5])] = stripcslashes($m[6]);
 		}
+	} else {
+		$atts = ltrim($text);
 	}
 	return $atts;
 }