Spurious time signature

[Thomas Ruedas]

Hi,
I am giving the last touch to a piano score I have recently completed and 
find that an acciaccatura causes a spurious time signature (Lilypond 
v.2.10.25). A slightly boiled-down snippet producing the crucial two 
measures from the code is given at the end.
The problem is that the acciaccatura on beat 1 of the second measure in the 
left hand somehow causes a repeated appearance of the signature 4/4: The 
first appearance is correct at the beginning of the measure before the 
acciaccatura, but then there is a second 4/4 after it.
Is there something wrong with my input or is it a bug? What can I do about 
it?
Thanks,
Thomas

\version "2.10.25"

i = \context Staff {
        \context Voice = "i"
        \voiceOne
\override Staff.TimeSignature #'style = #'()
\clef treble \key c \major 

\relative { \time 6/4 #(set-octavation 1) <as''' es des as>4 <es es,>8. <es 
es,>16 <as es des as>4 <es es,>8 <es es,>16 <as as,> <as es des as>4 <as 
es des as>8. <as es des as>16

\time 4/4 <as es as,>4~^\markup { \italic "a tempo"} <as es as,>8[~ <as es 
as,>32 #(set-octavation 0) ces, bes a] g8[~ g32 fis' f e] dis8[~ dis32 
#(set-octavation 1) ces' bes a] #(set-octavation 0)
}
}


ii = \context Staff {
        \context Voice = "ii"
        \voiceTwo
\override Staff.TimeSignature #'style = #'()
\clef bass \key c \major \time 4/4
\relative { \time 6/4 <d, a' d>2 <b fis' b> <as es' as>4 <fes ces' fes>

\time 4/4 \acciaccatura es,8 } <es, es>4 \clef treble <es' ges' bes'>4 
\clef bass #(set-octavation -1) <e,,! e,!>4 #(set-octavation 0) \clef 
treble <b! e'! g'!>
}


\score {
  \context PianoStaff <<
    \context Staff=upper <<
      \i
    >>
    \context Staff=lower <<
      \ii
    >>
  >>
  \layout {
    \context { 
\Score
}
    \context{
      \Staff
    }
  }
}
-- 
Protest against the arrest of Japanese anti-whaling campaigners:
http://www.email.greenpeace.org/snbyoobl_dzlyawqa.html
-----------------------------------
Thomas Ruedas
Department of Terrestrial Magnetism
Carnegie Institution of Washington
http://www.dtm.ciw.edu/ruedas/