Midi ghost notes appears with grace notes at high tempi.

[Pierre Perol-Schneider]

>I'm not top posting

Hi Bug squad,

This bug reminds me something but I did not find any trace about it (sorry
for the noise if it has already been reported).
It comes from a french discussion:
http://lilypond-french-users.1298960.n2.nabble.com/Fwd-Bug-Midi-avec-changement-de-tempo-td7583601.html

Snippet:

%%\version "2.18.2"
\version "2.19.35"

\score {
  \relative {
    \key ees \major
    \time 12/8
    \tempo 4 = 120

    %% un-comments the tempo and the 'ghost note' appears.
    %\tempo 4 = 190

    %% and getting worth at a higher tempo:
    %\tempo 4 = 200

      \grace { aes'32 d, ees } f4 d8
      \grace{ aes'32 } ees4 c8
      \grace{ aes'32 } bes,4 c8
      \grace{ ees32 } d4 ees8  |
    \bar "|."
  }
  \layout {
  }
  \midi {
    \context {
      \Staff
      midiInstrument = "soprano sax"
    }
  }
}

Cheers,
Pierre