This should avoid spamming build-log.txt with messages like:
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
LANGUAGE = (unset),
LC_ALL = (unset),
LANG = "en_US.UTF-8"
are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
OSX has shasum but not sha1sum, which is part of GNU coreutils.