misaligned incipits for clefs exceeding staff-lines

[Martin Straeten]

> I'm not top posting.

Hi,
in the current development version incipit-staves and main stave doesn't fit. 
See sample below:
The alignment is ok with 2.12.2

best regards, Martin

%% misaligned incipits for clefs exceeding staff-lines
\version "2.13.11"
\paper{ ragged-right=##t }

incipitClef =
#(define-music-function (parser location a b)  (string? string?)
#{ \set Staff.instrumentName = \markup{ \score{
                \new Staff \with { \remove "Time_signature_engraver" }
                { \set Staff.instrumentName = $b \clef $a s4 }
                \layout {}
        }}
#})

%expected alignment: ok for alto clef
\new Staff 
<< 
\incipitClef #"alto" #"name" 
\new Voice {\clef alto \relative c'{c4 d e f } }
>>

%incipit shifted upwards
\new Staff 
<< 
\incipitClef #"soprano" #"name" 
\new Voice {\clef treble \relative c'{c4 d e f } }
>>

%incipit shifted downwards
\new Staff 
<< 
\incipitClef #"baritone" #"name" 
\new Voice {\clef bass\relative c{c4 d e f } }
>>