Comments in /etc/libao.conf cause pulse output driver to fail

Example using pulseaudio output:

~ $ cat /etc/libao.conf
#HI
default_driver=pulse
~ $ ogg123 6.ogg 

Audio Device:   PulseAudio Output

Playing: 6.ogg
Ogg Vorbis stream: 6 channel, 44100 Hz
ERROR: Cannot open device pulse.

vs.

~ $ cat /etc/libao.conf
default_driver=pulse
~ $ ogg123 6.ogg 

Audio Device:   PulseAudio Output

Playing: 6.ogg
Ogg Vorbis stream: 6 channel, 44100 Hz
                                                                           
Done.
^C~ $ 

The specific libao version used is gentoo's libao-1.1.0-r1