In some cases kolabd fails to cleanly update IMAP mailbox after LDAP changes. That is usual when result_attribute value is in upper case. Mailbox modification seems to follow slightly different code path, by shortcutting to IMAP pykolab function...

Summary:
..."has_folder()" instead of going via "user_mailbox_exists()", which has a code to downcase mailbox name.

Do not shortcut to "has_folder()" function, use "user_mailbox_exists()" to downcase mailbox name before checking if it exists.

Test Plan: none

Reviewers: vanmeeuwen, machniak

Reviewed By: machniak

Subscribers: adomaitis, petersen, machniak, vanmeeuwen

Differential Revision: https://git.kolab.org/D571