When generating images using a non-interactive shell, the zerofree -v command generates hundreds of lines like this:

0.01%
0.02%
0.03%
0.04%
...

These lines are not very informative and burry useful information in the build log.

I would create a PR to remove the -v flag, but I assume there's a reason this flag was added in the first place? It would be nice if it could be removed, if the information is not really useful anyway. Otherwise maybe I can add a -v flag to build.sh, so verbosity can be controlled per build?