Like the other similar commits, we were doing the same work in all
code paths, just with a much more error-prone approach.
We can also now remove the now-unused finish_initial_narrow function.
Like the other commits in this series, we were already doing this in
all of the callers of load_messages; this centralizes that logic in a
less ad-hoc feeling way.
We no longer use or need the start_initial_narrow function.
Previously, each individual caller of load_messages that passed
num_before > 0 would do its own manual management of fetch_status;
now, we just do it inside load_messages.
This run_test helper sets up a convention that allows
us to give really short tracebacks for errors, and
eventually we can have more control over running
individual tests. (The latter goal has some
complications, since we often intentionally leak
setup in tests.)
This reverts commit bcdd12773e.
We need to do some improvements in handling FetchStatus for initial
narrows before this will be safe to deploy in production.
If individual messages arrive before we get the latest
messages from the server, they can create gaps in rendering,
and would often be offscreen anyway, so we just ignore them.
Tim Abbott
Steve Howell