slurs - once attached to stem ends, once to note heads

[Werner]

Hello,  

I got in a piece of music nearly all slurs and ties attached to the note heads.
But one slur is attached to the stem ends and I want it to be attached to the
note heads too. How to obtain this?

greetings

Werner


\version "2.12.2"
\include "deutsch.ly"

Tenor = {
\key g
\minor
\time 4/4
\set fontSize = #-1
\partial 4*1
r4 | r d r d | d8 d4 b8~ b2 r4 a r a( b) r r
fis4( | g) g a a g f e es d es d d'8( b)~ | b4 c b2 | 
r2 d8 d4. | r2 c8 c4. a4 b c d~ d2 b4 a
g8 b4. r4 g~ g2 c g c4 a b2.
\bar "|."
}
\score {
        \new ChoirStaff
        <<
% % %
                \context Staff = ZweiteZeile <<
                        \context Voice = ZweiteZeileErsteStimme {
                                \voiceOne
                                \relative c' { \clef F \Tenor }
                                }
%                       \context Voice = ZweiteZeileZweiteStimme {
%                               \voiceTwo 
%                               \relative c { \clef F \Bass }
%                               }
                >>
        \set Score.skipBars = ##t
        >>
\layout {
    indent = #0
    \context { \Score \remove "Bar_number_engraver" }
}
}