In the very infrequent case that we re-upload a file, the logic for
upload-release would have the existing SHA256SUM take precedence over
the new one -- despite uploading the new file.
Skip existing filenames (i.e. from the new file) when gathering
SHA256SUM metadata used to assemble `SHA256SUMS.txt`.
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.