For some reason build.py builds a lot of stuff that is completely
unrelated to the fonts themselves. Let's remove that!
Also the script is generating so much debug output that Hydra refuses to
evaluate the package — my fix is to pipe the output through grep to
filter out any log message below INFO, but I wish the script has a
built-in way to set the log level so that I don't have to do this hack
aa7ba46ebb