Remove quota using Cyrus::IMAP::Admin?

[Sebastian Hagedorn]

Hi,

you can remove the quota for a mailbox with cyradm by setting the quota to 
none:

$ cyradm cyrus
Password:
server> sq user/xxx none
remove quota
server>

But when I try to do the same using Cyrus::IMAP::Admin I get an error, 
because a number is expected as argument. Is that a bug or a feature? 
Here's my code:

$result = $imapcon->setquota("user/$user", "STORAGE", $quota);

If I set $quota to 'none', I get:

Error: xxx, STORAGE: none: not a number
-- 
    .:.Sebastian Hagedorn - Weyertal 121 (Gebäude 133), Zimmer 2.02.:.
                 .:.Regionales Rechenzentrum (RRZK).:.
   .:.Universität zu Köln / Cologne University - ✆ +49-221-470-89578.:.
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