Description:
------------
---
From manual page: http://www.php.net/pdo.rollback#refsect1-pdo.rollback-
returnvalues
---

manual page on the php.net documentation should state that PDO::rollback would 
throw a PDOException on certain conditions, like if no transaction existed.
The current documentation on the site says that it will return true on success or 
false on problems, and vaguely states that "It is an error to call this method if 
no transaction is active". this is vague and doesn't explain that an exception 
will be thrown.
This caused an un-handled exception in my code since in the upmost catch block I 
did a rollback to make sure that any open transaction is rolled-back. that lead 
to an un-handled exception... :-(

Expected result:
----------------
state in the documentation this possible PDOExcetion throwing