PitchedTrill somehow remembers pitch of 2nd note across bars

[Toine Schreurs]

Somehow, the pitch of the second note in a PitchedTrill is remembered
across bars. In the example below 6 bars with c trills are printed,
c-des c-des c-d c-d c-dis c-dis

bar 1 : d-flat as expected
bar 2 : d where a d-flat is expected
bar 3 : d natural where d is expected
bar 4 : d natural where d is expected
bar 5 : d where d-sharp is expected
bar 6 : d where d-sharp is expected

Is there a way to correct this?

\version "2.11.32"
\layout {
  indent = 0.0\cm
  ragged-right = ##f
}
\relative c' {
  \pitchedTrill c2\startTrillSpan des c\stopTrillSpan
  \pitchedTrill c\startTrillSpan  des c\stopTrillSpan
  \pitchedTrill c\startTrillSpan  d   c\stopTrillSpan
  \pitchedTrill c\startTrillSpan  d   c\stopTrillSpan
  \pitchedTrill c\startTrillSpan  dis c\stopTrillSpan
  \pitchedTrill c\startTrillSpan  dis c\stopTrillSpan
}

Toine Schreurs