Programming error at calculating line breaks in ChoirStaff with more than 4 parts

[Imruska]

Hello,

If I run the following file in 2.5.32 or 2.5.31 (did not test with other 
versions), I get the error message

calculating line breaks...
programming error: adding reverse spring, setting to unit
continuing, cross fingers

and in the first bar there is no space between the time signature and 
the first note.
--------------------
\version "2.5.31"
\include "deutsch.ly"
#(set-global-staff-size 16)
#(ly:set-option 'point-and-click #f)


global =  {
        \key f \major
        \time 4/4
        }

discantusNotes =  \relative g' {
        {
        r2 b4 c
        g a b c
        g a b c
        g a b c
        g a b c
        }
        }
        
        
altusNotes = \relative c' {
        {
        c4 d e f
        c d e f
        c d e f
        c d e f
        c d e f
        }
        }
        

tenorNotes = \relative g' {
        {
        g4 a b c
        g a b c
        g a b c
        g a b c
        g a b c
        }
        }


bassusNotes = \relative c' {
        {
        c4 d e f
        c d e f
        c d e f
        c d e f
        c d e f
        }
        }
        

quintusNotes = \relative c' {
        {
        c4 d e f
        c d e f
        c d e f
        c d e f
        c d e f
        }
        }
        

discantusstaff = \context Staff = "discantus" <<
        \global
        \context Voice = "discantus"
        {\discantusNotes}
        >>

altusstaff = \context Staff = "altus" <<
        \global
        \context Voice = "altus"
        {\altusNotes}
        >>

tenorstaff = \context Staff = "tenor" <<
        \global
        \context Voice = "tenor"
        {\tenorNotes}
        >>

bassusstaff = \context Staff = "bassus" <<
        \global
        \context Voice = "bassus"
        {\bassusNotes}
        >>

quintusstaff = \context Staff = "quintus" <<
        \global
        \context Voice = "quintus"
        {\quintusNotes}
        >>
        
\score {
        \context ChoirStaff <<
                \discantusstaff
                \altusstaff
                \tenorstaff
                \bassusstaff
                \quintusstaff
                >>
        
        }
%EOF

-------------------------
If you run this, you can see that there is no space after the time 
signature.
If I change the #(set-global-staff-size) to 18 or 24, I get the above 
message 5 times, but there *is* space after the time signature.
Size 20 is OK, no error message.
If I change the key to c\major, again I get the error message 5 times, 
and there is space after the time signature.
If I change \context ChoirStaff to \context Staff in the \score block, I 
get a sixth (empty) staff over the 5, but no error message.

This score originally contained lyrics, which I removed as it is 
irrelevant, but that's why the individual staves are created outside the 
\score block.

I made tests with some other 5,6 part music and always had this error 
message, but the missing space after the time signature was not present 
in each system. I made a test with a double choir 2x4 part work, it was 
OK, as there were two ChoirStaffs, each with only 4 parts.

Imruska