Re: [PATCH 3/7] trace: use warning() for printing trace errors

> Right now we just fprintf() straight to stderr, which can
> make the output hard to distinguish. It would be helpful to
> give it one of our usual prefixes like "error:", "warning:",
> etc.
>
> It doesn't make sense to use error() here, as the trace code
> is "optional" debugging code. If something goes wrong, we
> should warn the user, but saying "error" implies the actual
> git operation had a problem. So warning() is the only sane
> choice.
>
> Note that this does end up calling warn_routine() to do the
> formatting. So in theory, somebody who tries to trace from
> their warn_routine() could cause a loop. But nobody does
> this, and in fact nobody in the history of git has ever
> replaced the default warn_builtin (there isn't even a
> set_warn_routine function!).