Subbeaming and first measure grace notes

[Hans Aberg]

Is this a bug in the example below? The grace notes inhibit the called for 
subbeaming in the first measure; its OK in the following measure, and also when 
adding \partial. One can take away the triplet and replace with 1/16 notes.


----
\version "2.19.10"

\language "english"

music = \new Staff {
  \key e \minor

  \tempo 4 = 84
  \time 2/4

  \set subdivideBeams = ##t
  \set baseMoment = #(ly:make-moment 1/8)
  \set beatStructure = #'(2 2)

  \relative e' {
    \tuplet 3/2 {\grace {g16 fs} e8 fs16} g16 a16  b8 b |
    \tuplet 3/2 {\grace {g16 a} b8 c16} a16 c16  b8-. g8 |
  }
}

\score {
  \music
        \layout {}
}
----