Extra staff in lilypond 2.14.2

[D'Arcy J.M. Cain]

I upgraded Lilypond and found a weird change.  The input is below this
message.  On 2.12.3 it displays a single bass staff as I would expect.
On 2.14.2 it adds an extra, empty staff above with a treble clef and
the time signature but no lines or key.  This happens in all my LP
files.  Can someone tell me how to get rid of this?  I have attached
pictures of the output.

Thanks.

\version "2.10.10"
\include "english.ly"

#(set-global-staff-size 35)

\paper {
  #(set-default-paper-size "letter")
  before-title-space = 0
}

\header {
  title = "Test"
}

Common = {
  \time 4/4
  \key a \major
}

themusic = {
  <<
    \tempo 4 = 160
    \new Staff {
      \set Staff.midiInstrument = "acoustic bass"
      \Common
      \clef "bass_8"
      \relative c, { \time 3/4 a4. b8 c d e d c b4. a8 b c d c b a2. }
    }
  >>
}

\score {
  \themusic
  \layout { }
}


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D'Arcy J.M. Cain <address@hidden>         |  Democracy is three wolves
http://www.druid.net/darcy/                |  and a sheep voting on
+1 416 425 1212     (DoD#0082)    (eNTP)   |  what's for dinner.

lilypond.2.12.3.jpg
Description: JPEG image

lilypond.2.14.2.jpg
Description: JPEG image