Calling Variable in << \staff \\ \tabstaff >> fails with error Not enough synchronization points found

[kalegood]

Calling the variable melody gives error Not enough synchronization points found. Also fails when \new TabStaff is replaced with \new Staff.

This file compiles correctly when the music is explicitly stated inside the individual \staff contexts.

% Created on Sat Feb 09 15:10:04 EST 2013
\version "2.16.2"

\header {
    title = "Ode To Joy" 
    composer = "Beethoven" 
    tagline = "" 

}

\include "english.ly"

melody = {
    e e f g g f e d c c d e e4. d8 d2
    e4 e f g g f e d c c d e d4. c8 c2
    d4 d e c d e8 f e4 c d e8 f e4 d c d g,2
    e'4 e f g g f e d c c d e d4. c8 c2         
        \bar "|."

}

staffClassicalGuitar =  { 
    \time 4/4
    \tempo 4 = 100 
    \set Staff.midiInstrument = "acoustic guitar (nylon)"
    \key c \major
    \clef "G_8"
    \relative c' {  
        \melody
    }
}

staffTabGuitar = { 
    \new TabStaff {         
        \clef "moderntab"
        \relative c' {  
            \melody 
        }   
    } 
}
\score {
    <<
        \staffClassicalGuitar \\ \staffTabGuitar
    >>

    \midi {
    }

  \layout { indent=0\cm
  }
}

\paper {
}

[aspiers]

I have a worrisome feeling that this might require a substantially better parser than what the old stolen Frescobaldi code currently gives us. Assigning to 0.4.3 for investigation, but may have to postpone.