unwanted randomness while generating LilyPond output

[Werner LEMBERG]

Carl sent me his complete build (thanks!) for further investigation of
differences, and this unveiled an unpleasant surprise: We have
randomness in the construction of LilyPond EPS files.

I'm attaching an EPS output of both Carl's and my own build, together
with the corresponding source file; as can be seen, the EPS files
differ (I've checked that they display exactly the same).

Any idea how to fix this?  The randomness itself isn't bad, but it
makes it much harder to find problems, and it might prevent
reproducible documentation builds.  I suppose that somewhere in the
SCM code we need to sort a list or something like that while
generating output...


    Werner

werner.eps
Description: PostScript document

carl.eps
Description: PostScript document

%% Generated by lilypond-book
%% Options: 
[exampleindent=10.16\mm,indent=0\mm,line-width=160\mm,paper-height=845.047\pt,paper-width=597.508\pt,papersize='(cons
 (* 597.508 pt) (* 845.047 pt))]
\include "lilypond-book-preamble.ly"


% ****************************************************************
% Start cut-&-pastable-section
% ****************************************************************

#(ly:set-option 'eps-box-padding 3.000000)



\paper {
  #(set-paper-size '(cons (* 597.508 pt) (* 845.047 pt)))
  indent = 0\mm
  line-width = 160\mm
  % offset the left padding, also add 1mm as lilypond creates cropped
  % images with a little space on the right
  line-width = #(- line-width (* mm  3.000000) (* mm 1))
}

\layout {
  
}




% ****************************************************************
% ly snippet:
% ****************************************************************
\sourcefilename "snippets/adding-a-figured-bass-above-or-below-the-notes.ly"
\sourcefileline 0
%% DO NOT EDIT this file manually; it was automatically
%% generated from the LilyPond Snippet Repository
%% (http://lsr.di.unimi.it).
%%
%% Make any changes in the LSR itself, or in
%% `Documentation/snippets/new/`, then run
%% `scripts/auxiliar/makelsr.pl`.
%%
%% This file is in the public domain.

\version "2.24.0"

\header {
  lsrtags = "ancient-notation, chords, contexts-and-engravers"

  texidoc = "
When writing a figured bass, you can place the figures above or below
the bass notes, by defining the
@code{BassFigureAlignmentPositioning.direction} property (exclusively
in a @code{Staff} context). Choices are @code{#UP} (or @code{#1}),
@code{#CENTER} (or @code{#0}) and @code{#DOWN} (or @code{#-1}).

This property can be changed as many times as you wish. Use
@code{\\once \\override} if you don't want the override to apply to the
whole score.
"

  doctitle = "Adding a figured bass above or below the notes"
} % begin verbatim


bass = {
  \clef bass
  g4 b, c d
  e d8 c d2
}

continuo = \figuremode {
  <_>4 <6>4 <5/>4
  \override Staff.BassFigureAlignmentPositioning.direction = #UP
  %\bassFigureStaffAlignmentUp
  < _+ >4 <6>
  \set Staff.useBassFigureExtenders = ##t
  \override Staff.BassFigureAlignmentPositioning.direction = #DOWN
  %\bassFigureStaffAlignmentDown
  <4>4. <4>8 <_+>4
}

\score {
  <<
    \new Staff = bassStaff \bass
    \context Staff = bassStaff \continuo
  >>
}



% ****************************************************************
% end ly snippet
% ****************************************************************