2.16.0 Open string fingering marks have _ and ^ behave as ^

[Olivier Biot]

Dear all,

I think I just found a Lilypond bug.

The following snippet with fingerings does only show one "open string"
fingering while TWO have been written. The order of _ and ^ play no
role in this bug.

Expected behavior: both "\open" fingerings are displayed, one above
and one below selected note.

%%% BEGIN snippet
\version 2.16.0

\score {
  \new Staff \with {midiInstrument = #"cello"} {
    \relative c, {
      \key d \major
      \time 3/4
      \tempo "Allegro"
      \clef "bass"
      d8^\open_\open (ees^1_1 e^2_1 f^3_2 fis^1_3 g^2_4)
      gis^3_4 (a^\open_\open bes^1_1 b^2_1 c^3_2 cis^1_3)

      \bar "|."
    }
  }

  \layout {}
}
%%% END snippet

Best regards,

Olivier