Tab stems won't show up when using TabVoice

[Choan Gálvez]

Hi there.

I'm working on the transcription of some of my ukulele arrangements, 
which will be published both as Staff only / Staff + TabStaff / TabStaff 
only.

In order to get a useable TabStaff only output, I need to set 
`\tabFullNotation` in order to show rhythms, etc.

And I've just discovered that the stems won't show up when using 
TabVoice -- it doesn't matter if the voices are implicit, explicit or 
just one explicit voice.

% Example - Tab stems won't show up when using TabVoice
\version "2.15.38"

myNotes = { g' e' c' g }
myVoiceA = { e'8 d'8 c'4 e' c' }
myVoiceB = { c g c g }
myVoices = { << \myVoiceA \\ \myVoiceB  >> }
myMusic = {
  \myNotes
  \myVoices
}


\new TabStaff {
  \tabFullNotation
  \myNotes
  % stems are not shown when two implicit voices appear
  \myVoices
  <<
    % stems are not shown either when two explicit voices appear
    \new TabVoice {
      \voiceOne
      \myVoiceA
    }

    \new TabVoice {
      \voiceTwo
      \myVoiceB
    }
  >>
  <<
    % stems are not shown when _one_ explicit voice appear
    \new TabVoice {
      \myVoiceA
    }
  >>
  % everything fine again
  \myNotes
}
% End example

This problem exists in 2.14.2 too.

Should we call this a bug?

Best.
--
Choan Gálvez