a new lilypond build failure

[Thomas Bushnell BSG]

So delightfully, mftrace version 1.1.17 does indeed fix the previous
build problems.

But now there's a new, more subtle, one.  Normal Debian automatic
build procedure is to build things with input redirected from
/dev/null.

This causes a failure in running lilypond for documentation
generation.  The command invoked is from
lilypond-2.6.3/Documentation/user, and is

  /home/debian/lilypond-2.6.3/lily/out/lilypond --verbose 
/home/debian/lilypond-2.6.3/ly/generate-documentation

If the input is a terminal, this works fine, and prints the following
output:

  GNU LilyPond 2.6.3
  
  LILYPOND_DATADIR="/usr/share/lilypond/2.6.3"
  LOCALEDIR="/usr/share/locale"
  
  Effective prefix: "/usr/share/lilypond/2.6.3"
  Initializing FontConfig...
  adding font directory: /usr/share/lilypond/2.6.3/fonts/otf/
  adding font directory: /usr/share/lilypond/2.6.3/fonts/type1/
  adding font directory: /usr/share/lilypond/2.6.3/fonts/svg/
  Processing `/home/debian/lilypond-2.6.3/ly/generate-documentation.ly'
  
Parsing...[/usr/share/lilypond/2.6.3/ly/init.ly[/usr/share/lilypond/2.6.3/ly/declarations-init.ly[/usr/share/lilypond/2.6.3/ly/music-functions-init.ly][/usr/share/lilypond/2.6.3/ly/nederlands.ly][/usr/share/lilypond/2.6.3/ly/drumpitch-init.ly][/usr/share/lilypond/2.6.3/ly/chord-modifiers-init.ly][/usr/share/lilypond/2.6.3/ly/script-init.ly][/usr/share/lilypond/2.6.3/ly/scale-definitions-init.ly][/usr/share/lilypond/2.6.3/ly/grace-init.ly][/usr/share/lilypond/2.6.3/ly/midi-init.ly[/usr/share/lilypond/2.6.3/ly/performer-init.ly]][/usr/share/lilypond/2.6.3/ly/paper-defaults.ly[/usr/share/lilypond/2.6.3/ly/titling-init.ly]][/usr/share/lilypond/2.6.3/ly/engraver-init.ly][/usr/share/lilypond/2.6.3/ly/dynamic-scripts-init.ly][/usr/share/lilypond/2.6.3/ly/spanners-init.ly][/usr/share/lilypond/2.6.3/ly/property-init.ly]][/home/debian/lilypond-2.6.3/ly/generate-documentation.ly[/usr/share/lilypond/2.6.3/scm/documentation-lib.scm][/usr/share/lilypond/2.6.3/scm/document-functions.scm][/usr/share/lilypond/2.6.3/scm/document-translation.scm][/usr/share/lilypond/2.6.3/scm/document-music.scm][/usr/share/lilypond/2.6.3/scm/document-backend.scm][/usr/share/lilypond/2.6.3/scm/document-markup.scm]
  Writing "lilypond-internals.texi"...
  ]]
  
But if the input is redirected from /dev/null, it exits after
printing:

  LILYPOND_DATADIR="/usr/share/lilypond/2.6.3"
  LOCALEDIR="/usr/share/locale"
  
  Effective prefix: "/usr/share/lilypond/2.6.3"
  Initializing FontConfig...
  adding font directory: /usr/share/lilypond/2.6.3/fonts/otf/
  adding font directory: /usr/share/lilypond/2.6.3/fonts/type1/
  adding font directory: /usr/share/lilypond/2.6.3/fonts/svg/

And it does not generate any of the proper output files that should be
generated.

Moreover, the trailing newline after ...."/svg/" is not printed.

This premature exit reports exit status zero (which also caused
considerable pain in locating this as the source of the problems I'm
having!).

This happens with a lilypond that otherwise seems to work fine.

Thomas