Merge pull request #6188 from MrPetovan/bug/5928-protect-oauthexception

Protect OAuthException declaration to avoid conflict with php-pecl-oauth

library/OAuth1.php

@@ -3,9 +3,11 @@
 
 /* Generic exception class
  */
+if (!class_exists('OAuthException', false)) {
   class OAuthException extends Exception {
     // pass
   }
+}
 
 class OAuthConsumer {
   public $key;