Since KDE 4.11.1 kio_thumbnail fails to detect the proper mime type for FLAC files.

As far as i undersand, for all files in the directory, kio_thumbnail tries to determine the mime type of the files within the directory, e.g.:

kio_thumbnail(10151) ThumbnailProtocol::get: Wanting MIME Type: "video/x-matroska"

for mkv or e.g. for mp3: 

kio_thumbnail(10151) ThumbnailProtocol::get: Wanting MIME Type: "audio/mpeg"

Unfortunately, this is not done for flac files, which are "audio/flac" or "audio/x-flac".
Also I can confirm that this behavior appeared with KDE 4.11.1, so I assume it's a regression.

Reproducible: Always

Steps to Reproduce:
1. Enable dolphin debug
2. Enter directory 
3. Enable preview
4. Look at ~/.xessions-errors for output
Actual Results:  
kio_thumbnails fails to determine the mimetype of flac files

Expected Results:  
kio_thumbnails determines and outputs the mimetype of flac files