Renaming directories with subdirectories over IMAP

[Зинин Дмитрий Андреевич]

Hi,

I¹ve a problem with renaming directories with subdirectories.

In root directory I create directory named ³lvl1² with subdirectory ³lvl2²

When I rename directory lvl1 to lvl1-new I get:
1. /lvl1-new with subdir lvl2 but I can use only /lvl1-new and not
/lvl1-new/lvl2 
2. /lvl1 with subdir lvl2 but I can use only /lvl1/lvl2 and not /lvl1

Is it a feature or a bug?

If bug is there a fix?

PS: CentOS 6.6 and Dovecot 2.0.9-7 from official repository with all
updates.

Best regards,
Dmitriy