polyphonic tuplets

[Magnus Lewis-Smith]

\version "2.8.3"
\relative {
  \time 2/4

  c2 | %% 'XXX' - all is OK if this line is not present

  %% OK
  <<
    \times 2/3 { e8 e e e e e }
    \\
    \times 2/3 { c8 c c c c c }
  >> |

  %% BAD
  %% if 'XXX' exists, tuplet brackets disappear with compile errors:
  %% 'programming error: must have Item for spanner bound'
  \times 2/3 {
    <<
      { e8 e e e e e }
      \\
      { c8 c c c c c }
    >> |
  }
}