Make doc is broken

[Phil Holmes]

I think Reinhold's commit cfcb9efdbd7c6600fc89fc912ba80529010b31e7 has 
broken make doc.  I've just done a clean build (fresh build directory) and 
get this at the end of a failed make doc:

LILYPOND_VERSION=2.15.9 /usr/bin/python 
/home/phil/lilypond-git/scripts/lilypond-book.py -I 
/home/phil/lilypond-git/input/regression/musicxml/ -I ./out-www -I 
/home/phil/lilypond-git/input -I /home/phil/lilypond-git/Documentation -I 
/home/phil/lilypond-git/Documentation/snippets -I 
/home/phil/lilypond-git/input/regression/ -I 
/home/phil/lilypond-git/Documentation/included/ -I 
/home/phil/lilypond-git/build/mf/out/ -I 
/home/phil/lilypond-git/build/mf/out/ -I 
/home/phil/lilypond-git/Documentation/pictures -I 
/home/phil/lilypond-git/build/Documentation/pictures/./out-www --process='/home/phil/lilypond-git/build/out/bin/lilypond 
-I /home/phil/lilypond-git/input/regression/musicxml/ -I ./out-www -I 
/home/phil/lilypond-git/input -I /home/phil/lilypond-git/Documentation -I 
/home/phil/lilypond-git/Documentation/snippets -I 
/home/phil/lilypond-git/input/regression/ -I 
/home/phil/lilypond-git/Documentation/included/ -I 
/home/phil/lilypond-git/build/mf/out/ -I 
/home/phil/lilypond-git/build/mf/out/ -I 
/home/phil/lilypond-git/Documentation/pictures -I 
/home/phil/lilypond-git/build/Documentation/pictures/./out-www -dbackend=eps 
--formats=ps,png,pdf  -dinclude-eps-fonts -dgs-load-fonts --header=doctitle 
--header=doctitlecs --header=doctitlede --header=doctitlees --header=doctitlefr 
--header=doctitlehu --header=doctitleit --header=doctitleja --header=doctitlenl 
--header=doctitlezh --header=texidoc --header=texidoccs --header=texidocde  
--header=texidoces --header=texidocfr --header=texidochu --header=texidocit  
--header=texidocja --header=texidocnl --header=texidoczh -dcheck-internal-types 
-ddump-signatures -danti-alias-factor=2' --output=./out-www --format=texi-html 
--verbose  --lily-output-dir 
/home/phil/lilypond-git/build/out/lybook-db --load-custom-package=book-musicxml-testsuite.py 
out-www/collated-files.tely
langdefs.py: warning: lilypond-doc gettext domain not found.
Traceback (most recent call last):
 File "/home/phil/lilypond-git/scripts/lilypond-book.py", line 693, in 
<module>
   main ()
 File "/home/phil/lilypond-git/scripts/lilypond-book.py", line 624, in main
   files = do_options ()
 File "/home/phil/lilypond-git/scripts/lilypond-book.py", line 610, in 
do_options
   print imp.load_source ("book_custom_package%s" % nr, i)

In my previous succesful make, there was 
no --load-custom-package=book-musicxml-testsuite.py  option.

git grep -e 'load-custom-package'
input/regression/musicxml/GNUmakefile:LILYPOND_BOOK_FLAGS 
+= --load-custom-packa

This line was added with the commit above.  Could you have a look at this, 
please, Reinhold?

--
Phil Holmes