[O] BUG: setting comment-use-syntax to nil causes problems in Emacs head

[Le Wang]

This value was changed from the default of 'undecided to nil in 4d00c5bf4 .

In turn, it exposes bug in Emacs HEAD, see:
http://debbugs.gnu.org/cgi/bugreport.cgi?bug=12583

Is there a compelling reason for this change?

-- 
Le