transcode 1.1.4 hangs after video frame extraction

I have a script that extracts frames from a video, at fixed intervals:

    # Define the video import module for transcode
    case $EXT in
      avi)      IMP="ffmpeg" ;;
      mp4)      IMP="mov"    ;;
      mpg)      IMP="mpeg2"  ;;
    esac
  
    # Extract an image every ten seconds from each file
nice -n 19 transcode -q 0 -o $WORK/$FIL.img/png/$FIL.img -y im -F png -x 
$IMP,null -i $STOR/$FIL.$EXT -c \
0:00:00-0:00:00.1,0:00:10-0:00:10.1,0:00:20-0:00:20.1,0:00:30-0:00:30.1,0:00:40-0:00:40.1,0:00:50-0:00:50.1,\
0:01:00-0:01:00.1,0:01:10-0:01:10.1,0:01:20-0:01:20.1,0:01:30-0:01:30.1,0:01:40-0:01:40.1,0:01:50-0:01:50.1,\
0:02:00-0:02:00.1,0:02:10-0:02:10.1,0:02:20-0:02:20.1,0:02:30-0:02:30.1,0:02:40-0:02:40.1,0:02:50-0:02:50.1,\
0:03:00-0:03:00.1,0:03:10-0:03:10.1,0:03:20-0:03:20.1,0:03:30-0:03:30.1,0:03:40-0:03:40.1,0:03:50-0:03:50.1,\
....

This works fine in transcode 1.0.x. In transcode 1.1 (I just tested 
1.1.4), the frames are extracted correctly, but the process doesn't exit.

I'm seeing this on Linux (Debian sid), but it also came up in OSX a year 
or so ago. Some changes were made to the code that removed the hang on 
OSX (I haven't tested 1.1.4, but 1.1.3 works fine on Leopard).

This is a production system, so I've had to revert to transcode 1.0.6. 
Suggestions?

Cheers,
Dave