output-distance.py

[Graham Percival]

script/output-distance.py is broken.  I suspect that the general
out/lybook-db/ thing is the problem -- when I look at self.missing and
self.added (say, adding a print to line 818 of
scripts/build/output-distance.py ), I see tons and tons of files.

This is confirmed by the following test:
address@hidden:~/tmp$ ls
2.13.3  lilypond-2.13.3-0.test-output.tar.bz2
2.13.5  lilypond-2.13.5-HEAD.test-output.tar.bz2
address@hidden:~/tmp$ find . -name "*.ly" | xargs grep
accidental-ancient
./2.13.3/regression/out-test/11/lily-6a1f0270.ly:\sourcefilename
"/home/lilypond/gub/target/linux-x86/src/lilypond-git.sv.gnu.org--lilypond.git-master/input/regression/accidental-ancient.ly"
./2.13.5/regression/out-test/b4/lily-397060d1.ly:\sourcefilename
"/main/src/gub/target/linux-x86/src/lilypond-git.sv.gnu.org--lilypond.git-master/input/regression/accidental-ancient.ly"
address@hidden:~/tmp$

I can't see how output-distance.py could track files across such changes.

So... how are the directories and hashes generated?  If it's
machine-specific, then we have a hope -- we can't generate a
comparison between 2.13.3 and 2.13.5, but at least later comparisons
will be possible.

If the hashes are based on the contents of the file, which I fear,
then we're hosed whenever we update the version number of the
regtests.  :(

Cheers,  (?)
- Graham

PS I suppose we could change the hashing function to disregard any
\version commands... but that still strikes me as fragile.  Maybe the
best solution is to not use the lybook-db for input/regressions ?