Unexpected output of "notmuch new --quiet"

[Ralph Seichter]

* David Bremner:

> I guess if you have a simple way of distinguishing the cases which you
> want to consider as errrors, we can revisit the idea.

Personally, I'd go with these decreasing levels of severity:

  Fatal: Execution must stop immediately to prevent damage, error
  message may or may not be displayed before exiting the process.

  Error: Serious trouble, program may or may not be able to recover,
  user intervention required.

  Warning: Minor trouble, program will recover without user
  intervention.

  Notice: Inform the user of a less-than-ideal situation (non-mail file
  found, deprecated functionality used, etc). Program will ignore the
  cause and carry on.

I don't know if this is a fit for Notmuch, but it would be great if I
could prevent warnings and notices from being reported by using a
command line option.

-Ralph