remove first empty staff line

[Helge Kruse]

Hello,

I have a variation in a piece where most is placed in the bass hand 
except the last measure. I tried to use the \RemoveEmptyStaffContext. As 
documented this does not remove the staff in the first line.

Unfortunately this one additional empty staff line causes an additional 
page. How can I achieve that the treble staff appears only in the last line?

The staff in the second line has a left "open" end. I would expect a bar 
before the clef.

Regards, Helge


#(ly:set-option 'delete-intermediate-files #t)

\version "2.13.11"

trebleStaff = \relative c' {
    s1.*8 |
    R1. R1. R1.
    r2. r4 c8 d4 <c f>8~ \bar "||"
}

bassStaff = \relative c {
    \key bes \major
    \time 12/8  
    \clef bass

    % is ignored as long as ued outside of a chord (LSR/Item?id=214)
    \set fingeringOrientations = #'(down)

    <f,-4>4 <f'-1>8 ees4-+ r8 c4-+ r8 a4 r8 | % 1
    bes4 bes8 d4 r8 f4 r8 gis4 r8 | % 2
    <f,-4>4 f'8 es4 r8 c4 r8 es4 r8 | % 3
    f4 es8 gis 4 r8 a4 r8 c4 r8 | % 4
    <bes,-4>4 bes'8 gis4 r8 f4 r8 gis4 r8 | % 5
    <bes,-4>4 bes'8 gis4 r8 f4 r8 d4 r8 | % 6
    <f,-4>4 f'8 es4 r8 c4 r8 bes4 r8 | % 7
    a4 r8 es'4 r8 d4 r8 gis4 r8 | % 8
    g,?4 g8 a4 r8 bes4 r8 g4 r8 | % 9
    c4 c8 bes4 r8 as4 r8 g?4 r8 | % 10
    <f-4>4 f'8 es4 r8 d4 r8 gis4 r8 | % 11
    g,?4 a8 bes4 c8~c2.
}

\score {
        \new PianoStaff <<
                \new Staff \trebleStaff
                \new Staff \bassStaff
        >>
        \layout {
                \context {
                        \RemoveEmptyStaffContext
                }
        }
}