ties and barline checks

[Victor Eijkhout]

Personally, I don't find the barline checks here objectionable:

\score { <<

 \relative c' {\time 2/4
   <c e c'>2 | (<c e c'>4)
   <a d f>4 | (<a d f>2)
 }

>> }

\version "2.11.39"


but lilypond seems to think otherwise:

Parsing...
tie.ly:4:16: error: syntax error, unexpected '('
   <c e c'>2 |
               (<c e c'>4)
tie.ly:5:15: error: syntax error, unexpected '('
   <a d f>4 |
              (<a d f>2)