Problem with initial grace note

[Patrick Karl]

When I compile the following:

\version "2.12.2"
S  =   \relative g'' {
                \appoggiatura g16 f1
}

\score {
        \new ChoirStaff <<
                \time 4/4
                \new Staff { \S  }
        >>
        \layout { }
        \midi { }
}

I get the output attached, which shows two instances of the time  
signature with the grace note, in this case an appoggiatura, stuck  
between and a long, greatly downwards displaced (apparently in order  
to avoid collision with the 2nd time sig) slur connecting to the main  
note.

In addition, the log file shows two instances of the following error:

> programming error: Going back in MIDI time.
> continuing, cross fingers


Note that the duplicated time signature  does not occur if the "\time  
4/4" statement is omitted; the two MIDI errors, however, still occur.