‘exit’ is pulled in for the interactive interpreter as a side effect
of the site module; this can be disabled with python -S and shouldn’t
be relied on.
Also, use the NoReturn type where appropriate.
Signed-off-by: Anders Kaseorg <anders@zulip.com>
This is a preparatory commit for using isort for sorting all of our
imports, merging changes to files where we can easily review the
changes as something we're happy with.
These are also files with relatively little active development, which
means we don't expect much merge conflict risk from these changes.
Previous cleanups (mostly the removals of Python __future__ imports)
were done in a way that introduced leading newlines. Delete leading
newlines from all files, except static/assets/zulip-emoji/NOTICE,
which is a verbatim copy of the Apache 2.0 license.
Signed-off-by: Anders Kaseorg <anders@zulipchat.com>