Upstream: NGX_HTTP_GATEWAY_TIME_OUT after upstream timeouts. There is no real difference from previously used 0 as NGX_HTTP_* will become 0 in ngx_http_upstream_finalize_request(), but the change preserves information about a timeout a bit longer. Previous use of ETIMEDOUT in one place was just wrong. Note well that with cacheable responses there will be a difference (code in ngx_http_upstream_finalize_request() will store the error in cache), though this change doesn't touch cacheable case.