doc build failure: something weird with fink libpng, netpbm, and make web

[Graham Percival]

When I try to build the docs, I get the following error:

Invoking `pngtopnm lily-39f2b92ff8.png.old | pnmscale -reduce 2 
2>/dev/null | pnmtopng -compression 9 2>/dev/null > lily-39f2b92ff8.png'...
dyld: Library not loaded: /sw/lib/libpng.3.dylib
  Referenced from: /sw/bin/pngtopnm
  Reason: Incompatible library version: pngtopnm requires version 
20.0.0 or later, but libpng.3.dylib provides version 4.0.0
GS exited with status: 34048command failed...  (much more junk)


I sent an email to the libpng/netpbm fink packager complaining about 
this, but after a bit of investigation I've discovered that if run the` 
pngtopnm lily-39f2b92ff8.png.old | ...' command by itself, it works 
fine.  otool reports sensible-looking info:

tsubasa:~/usr/src/lilypond/input/lsr/ancient gperciva$ otool -L 
/sw/bin/pnmtopng
/sw/bin/pnmtopng:
        /sw/lib/libnetpbm.10.dylib (compatibility version 11.0.0, 
current version 11.26.0)
        /sw/lib/libpng.3.dylib (compatibility version 20.0.0, current 
version 20.0.0)
        /usr/lib/libz.1.dylib (compatibility version 1.0.0, current 
version 1.2.3)
        /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, 
current version 88.3.4)
        /usr/lib/libgcc_s.1.dylib (compatibility version 1.0.0, current 
version 1.0.0)


I have no clue how pngtopbm managed to find a "version 4.0.0".  Does 
anybody have any hints?

This only stopped working recently (after I upgraded to the latest 
version of fink's netpbm in the middle of last week), but since the 
command-line version works ok, I'm not 100% certain that the problem was 
caused by the fink package and not the lilypond doc build process.

I'm making the docs with:

ulimit -n 4096
if [ -e out-www/lilypond.texi ]; then rm out-www/lilypond.* ; fi;
nice make 
LILYPOND_EXTERNAL_BINARY=~/Apps/LilyPond.app/Contents/Resources/bin/lilypond 
web


Cheers,
- Graham