Staff switch line (documentation?) bug

[Yuval Harel]

Hi,

I noticed that in some situations \showStaffSwitch works where {\set  
PianoStaff.followVoice = ##t}
produces seemingly-buggy results. Are they expected to produce the same  
behavior?
The documentation  
(http://lilypond.org/doc/v2.5/Documentation/user/out-www/lilypond/Staff-switch-lines.html)  
appears to hint they are the same (though this is not written explicitly)  
and shows an example using {\set PianoStaff.followVoice = ##t}, which as  
far as I can see, is not usable.

The following example demonstrates the issue: in addition to the expected  
staff-switch line, a
redundant one is produced is the right hand staff, although that voice  
does not cross staves.
Using \showStaffSwitch instead of {\set PianoStaff.followVoice = ##t}  
produces the expected behavior.

\version "2.4.2"

\new PianoStaff <<
    \context Staff=RH { c'1 | \voiceOne c'1 }
    \context Staff=LH {
        \clef bass
        c1 |
        \set PianoStaff.followVoice = ##t
        \change Staff=RH \voiceTwo
        c'1
    }
> >


Thanks,
        Yuval