grace notes (lily 2.6.4 Windows (not cygwin))

[Frédéric Bron]

With this small example, I get an error and wrong output (graces notes 
grouped in a chord with the next note!).
Note that if you just remove "\clef treble", the bug disappears!!

Fred

\version "2.6.4"

\include "english.ly"

<<
       \new Staff {
               \clef treble
               \relative {
                       \acciaccatura { b16[ cs] } d4.(\p cs16 b)
                       a2
               }
       }
>>

d:/Softs/LilyPond/usr/share/lilypond/2.6.4/ly/grace-init.ly:26:8: 
warning: can't end slur
   s1*0
       )
xuxu.ly:9:51: warning: adding note head to incompatible stem (type = 16)
                       \acciaccatura { b16[ cs] }
                                                  d4.(\p cs16 b)
xuxu.ly:9:51: warning: maybe input should specify polyphonic voices
                       \acciaccatura { b16[ cs] }
                                                  d4.(\p cs16 b)[1]
Preprocessing graphical objects...
xuxu.ly:9:43: warning: removing beam with less than two stems
                       \acciaccatura { b16
                                          [ cs] } d4.(\p cs16 b)