verify regression tests

[Marc Hohl]

Hello list,

I got strange results with the regression tests, and studying the
CG more carefully, I spotted some differences:

http://lilypond.org/doc/v2.17/Documentation/contributor/regtest-comparison

says that you should do

make test-baseline && make check

[changed the code; if needed 'make']

make test-redo && make check (the latter is rather implicitly hidden in 
the text)

After all looks good, do a

make test-clean && make check

to restore the system to a clean state.

http://lilypond.org/doc/v2.17/Documentation/contributor/verify-regression-tests

is more overviewish, but it lacks the final

make check

which is needed after make test-clean, IIUC.

I can cook up a patch for that, but I want to make sure that the changes are
correct.

Regards,

Marc