Hide time signature in final partial measure

[Thomas Liggett]

Hi all,

In this score with a final partial measure (to balance the initial partial 
measure), what is the best way to hide the time signature in the final measure? 
The \omit Staff.TimeSignature has no apparent effect.

Thanks,
Thomas

%%%

\version "2.19.82"

global = { \time 4/4 
           \partial 4 s4
           \repeat volta 2 { s1 }
           \alternative { 
             { s1 } 
             { \omit Staff.TimeSignature \time 3/4 s2. } }
           \bar "|."
}

myNotes = \relative c' { e4 f2 g a b c d4 }

\score {
  \new Staff 
  << \new NullVoice { \global }
     \new Voice { \myNotes } >>
}

%%%