if (!t) {
        return null;
    }

    if (numericRE.test(t)) {
        if (t < 150000) {
            // We could use the golang.org/cl/ handler here, but
            // avoid some redirect latency and go right there, since
            // one is easy. (no server-side mapping)
            return "https://github.com/golang/go/issues/" + t;
        }
        return "https://golang.org/cl/" + t;
    }

			// but for the golang.org/x repos it seems to be significantly (~2x)
			// faster than copying one file at a time (via filepath.WalkDir),
			// apparently due to high latency in 'adb' commands.
			if err := adb("push", modDir, deviceModDir); err != nil {
				return 0, err
			}
		} else {
			if err := adb("exec-out", "mkdir", "-p", deviceCwd); err != nil {
				return 0, err
			}