This seems to have been causing the travis production suite to fail.
It's a direct consequence of removing travis' giant library of apt
sources.list files; now that those are gone, there aren't copies of
all these extra packages available anyway.
This directory contains scripts that are used in building, managing,
testing, and other forms of work in a Zulip development environment.
Note that tools that are also useful in production belong in
scripts/ or should be Django management commands.