\repeatTie tie direction in polyphonic systems

[maestraccio]

> I'm not top posting.

%% the \repeatTie command resets tie direction to \tieNeutral
in polyphonic systems.
\version "2.10.33"
\paper{ ragged-right=##t }
\relative c''
{
 
  {
   \repeat volta 2 {c1~} \alternative {{c4 b a g }{c4\repeatTie d c b }}
  }
 \\
  {
   a1~|a4 g f e |a4\repeatTie b a g
  }
 >>
}

\score
{
 \new Staff
   \set Staff.instrumentName = "polyphonic"
 \layout { }
 \midi { }
}