Staff lines running past final bar on staff

[Nick Payne]

See attached. If I have an ossia at the beginning of a staff, the lines on
the preceding staff run past the final barline. How do I prevent this? I'm
creating the ossia with 

        << 
        {
                % normal notes here
        }
        \new Staff \with {
                alignAboveContext = #"1"
                fontSize = #-4
                \override StaffSymbol #'staff-space = #(magstep -4)
                \override StaffSymbol #'thickness = #(magstep -4)
                \remove "Time_signature_engraver"
        }
        { 
                \clef "treble_8"
                \key e \minor
                        % ossia notes here
        } 
        >>

Nick

ossia.png
Description: PNG image