"-newaudio" in avconv

cd ~/eev-videos/

# This works:
ffmpeg -i video2-video.mp4 \
       -i video2-audio.mp3 \
       -vcodec copy \
       -acodec copy \
       -acodec copy \
       video2.mp4 \
       -newaudio

# This does not!
# The error message is "Missing argument for option 'newaudio'"...
avconv -i video2-video.mp4 \
       -i video2-audio.mp3 \
       -vcodec copy \
       -acodec copy \
       -acodec copy \
       video2.mp4 \
       -newaudio