Parsing timezone allows minutes to be missing or present

[tisonkun]

chrono supports:

Spec.	Example	Description
%#z	+09	Parsing only: Same as %z but allows minutes to be missing or present.

in strptime - https://docs.rs/chrono/latest/chrono/format/strftime/index.html.

jiff's %#z is identical to %z that accepts only [+-]HHMM[SS].

Is it possible to add similar support? The format seems what PostgreSQL's timestamptz uses and now blocks launchbadge/sqlx#3511.

[BurntSushi]

I think we should do this, but I think what you're doing in that sqlx PR is not quite right. You're using strptime in the first place because parsing a Zoned requires the time zone annotation. But if you parse into a Timestamp without strptime at all, then it will work just fine. And a Timestamp more accurately models what PostgreSQL is giving you. You generally should only use a Zoned when you have a time zone.

I think I'd prefer not adding more format specifiers for this, and instead just make the existing %z and %:z specifiers parse successfully when minutes aren't present. I guess the downside there is that you might specifically want there to be four digits if you're trying to match an existing format. Or when you're printing. So maybe we can't do that and we do indeed need additional specifiers. Sigh. But this will also apply to %V too.