Again: Questions about Stem #'length

[Marc Hohl]

Despite of the answers that were given
(and which normally are sufficient enough for a workaround):

can someone explain to me why lilypond still (at least sometimes)
displays stems when I
\override Stem #'length = #0?

Thanks in advance

Marc

%%%%

\version "2.13.4"

test = \relative c' {
   c4 d e f
   g a b c
   \stemUp
   c, d e f
   g a b c
   \stemDown
   c, d e f
   g a b c
}

\score {
  \new Voice {
    \test
    \break
    \override Voice.Stem #'length = #0
    \test
  }
}