partcombine problem: ties

[Dean Dierschow]

I've found a problem with partcombine, using 2.13.5.

I have some cases where I am combining two voices.  The first voice 
has a note that is tied through several measures.  Partway through
this, the second voice is added.  Apparently, partcombine becomes
confused and bails out for this section.

Here is a relevant snippet.

\new Voice { \partcombine
  \relative c'' {
    \time 4/4 g1 g r g~ g r g g r g~ g
  }
  \relative c' {
    r1 e r r e r r g r r g
  }
}

Dean