Cannot change download priority for directories

[apf]

• Location: "Torrents" view, torrent item expanded, file list
• Action: Change download priority of a whole directory (all of its files) by selecting "Normal/High/Off" from the dropdown menu.
• Bogus behavior: instead of priority change, error message: "Invalid directory was given"

(in the underlying rtorrent client the feature works correctly)

[apf]

server: nginx 0.7.67-3+squeeze2 && php-cgi 5.3.3-7+squeeze3
rtwi version: 0.3.6b
Client version: 0.8.9
Library version: 0.12.9

lang =          en
site_theme =    default_ajax
dodirtree =     true
ajax =          true
dht =           true
download =      true
erase =         true
flags =         false
hidedirtree =   true
language =      true
refresh =       true
throttle =      true