bug report #436020 by joshuajabbour: Allow exclamation mark in URL, as per RFC 1738.

link.module

@@ -673,8 +673,8 @@ function link_validate_url($text) {
   // Pattern specific to internal links.
   $internal_pattern = "/^([a-z0-9_\-+\[\]]+)";
 
-  $directories = "(\/[a-z0-9_\-\.~+%=&,$'():;*@\[\]]*)*";
-   // Yes, four backslashes == a single backslash.
+  $directories = "(\/[a-z0-9_\-\.~+%=&,$'!():;*@\[\]]*)*";
+  // Yes, four backslashes == a single backslash.
   $query = "(\/?\?([?a-z0-9+_|\-\.\/\\\\%=&,$'():;*@\[\]]*))";
   $anchor = "(#[a-z0-9_\-\.~+%=&,$'():;*@\[\]]*)";