Describe the feature you'd like to add to nginx

nginx currently logs an upstream response is buffered to a temporary file messages to error_log with warn as the log level. This is the expected default behavior and not a bad thing. It would make much more sense for this to be notice or likely even info. Logging warnings shouldn't happen when nothing concerning is happening. I think it should likely be info rather than notice because this is a completely expected, normal behavior and is not a sign of unexpected performance overhead when configured to handle uploads this way.

Describe the problem this feature solves

It would reduce the noise in error_log when the log level is set to warn rather than err. Cleaning up things like this could enable changing the default log level to warn and therefore communicating more issues to system administrators by default.

Additional context

This is the relevant code:

        p->temp_file->log_level = NGX_LOG_WARN;
        p->temp_file->warn = "an upstream response is buffered "
                             "to a temporary file";