Can't allocate notes to lowest string in tab

[Andrew Wilson]

> I'm not top posting.

Lilypond doesn't seem to be capable of allocating notes to the bottom
string of a non-standard tab staff.  I discovered the problem while
defining a staff for five  string bass guitar, but it's reproducable
with a 2 string tab.  The first five  notes should be on the b string,
the first note that shows up is the open e string.

\version "2.10.33"

% can't allocate notes on lowest string

\paper{ ragged-right=##t }

notes = \relative c, {
  b c cis d dis e f fis
}


\new StaffGroup <<
  \new Staff {
    \clef bass
    \notes
  }

  \new TabStaff <<
    \set TabStaff.stringTunings = #'( -20 -25 )
    {
      \notes
    }
  >>
>>