0.6.9->0.6.10 upgrade: "Could not set DTIM period for kernel driver"

[Alexey Yudichev]

After upgrading 0.6.9->0.6.10 I started to get this upon startup:

 Could not set DTIM period for kernel driver
 wlan2: Unable to setup interface.
 rmdir[ctrl_interface]: No such file or directory

 Driver is nl80211 (ath9k).

 Quick googling also finds similar bug reported on gentoo:
 http://bugs.gentoo.org/show_bug.cgi?id=301191
 Downgrading back to 0.6.9 solves it.

 Is it a bug or I am missing something?