d, ok := ctx.Deadline()
	if !ok {
		return true
	}
	return t.Before(d)
}

// knownRoundTripperImpl reports whether rt is a RoundTripper that's
// maintained by the Go team and known to implement the latest
// optional semantics (notably contexts). The Request is used
// to check whether this particular request is using an alternate protocol,

		key, val, _ := cfg.GetArchEnv()
		fmt.Fprintf(h, "%s=%s\n", key, val)

		if cfg.CleanGOEXPERIMENT != "" {
			fmt.Fprintf(h, "GOEXPERIMENT=%q\n", cfg.CleanGOEXPERIMENT)
		}

		// TODO(rsc): Convince compiler team not to add more magic environment variables,
		// or perhaps restrict the environment variables passed to subprocesses.
		// Because these are clumsy, undocumented special-case hacks