Issue 1652 in lilypond: Assertion error when line-count of StaffSymbol set to 0 and one uses a note in the middle of the (non-existant) staff

[lilypond]

Status: Accepted
Owner: address@hidden
Labels: Type-Defect Priority-High

New issue 1652 by address@hidden: Assertion error when line-count of  
StaffSymbol set to 0 and one uses a note in the middle of the  
(non-existant) staff
http://code.google.com/p/lilypond/issues/detail?id=1652

{
\stopStaff
\override Staff . StaffSymbol #'line-count = #0
\startStaff
b'
}

Leads to:
Assertion failed: (d == 1 || d == -1), function at,  
file ../flower/include/drul-array.hh, line 35.

This arises in ledger-line-spanner.cc on lines 329-330, where the  
Drul_array is passed the value 0.  Interestingly, the staff_extent is empty  
(the up value is lower than the down value), which may be causing the  
problem.