syntax change?

[David Bobroff]

In a slightly earlier version the following snippet produced what I
wanted.  That is, six eighth-note triplets; three pointing up and three
pointing down and intermeshed like this:

  _______
  |  |  |
  *  *  *
*  *  *
|  |  |
------- 

With slurs/ties conneting adjacent note heads.

Now, in version 2.1.23 the noteheads on the up stems are invisible.  Is
this due to a change in the way contexts are handled, or is this a bug? 
This version was compiled from CVS ChangLog 1.718.

Thanks,

David

\version "2.1.23"

inv = { \override NoteHead   #'transparent  = ##t       
        \override Rest   #'transparent = ##t
        \override Stem   #'transparent = ##t
        \override Dots   #'transparent = ##t 
    }

unv = { \revert NoteHead #'transparent
        \revert Rest #'transparent
        \revert Stem #'transparent
        \revert Dots #'transparent
    }

\score{
    \notes \relative c'{
        \override Staff.TupletBracket   #'transparent = ##t 
        \set tupletSpannerDuration = #(ly:make-moment 1 4)
        r2 \times 2/3 {
                << {\stemDown e8-[-( \inv e-) \unv e-( \inv e-) \unv e-(-] \inv
e-)} 
           \\ {\stemUp s8 e-[ \inv e \unv e \inv e \unv e-]}>>

            }
        }
    }