Unwanted explicit flats

[Karl Hammar]

For both:
$ dpkg -l lilypond-snapshot | tail -1
ii  lilypond-snaps 2.4.2-1        A program for typesetting sheet music
$ grep ChangeLog CVS/Entries
/ChangeLog/1.3417/Sat Apr  9 19:46:03 2005//

score below gives me an unwanted explicit flat in
the next to last measure.

\version "2.4.2"

\relative c'' {
  \override Score.BarNumber  #'break-visibility = #end-of-line-invisible
  \mark #03
  \clef treble
  \key c \minor
  a2 b |
  d1 |
  \mark #04
  \set Score.currentBarNumber = #1
  d2 es8. as,16 bes8 c |
%         ^     ^  theese two are rendered with flats
  d1
}

This is a condenced example of http://aspodata.se/motett/noter/act1.ly.
See act1.pdf at same site, page 5, Be staff, measure 5.
Similar errors are all over the place.

When comment the \set Score.currentBarNumber = #1, the flats disappear.

Regards
/Karl