gotip: don't set User-Agent for http.DefaultTransport

This code was copied from ./internal/version in CL 206537 with the
intention of making the gotip command more consistent with the other
golang.org/dl/go... commands. However, the gotip command does not
use net/http at all, so setting a custom user agent has no effect.

Change-Id: I1632aa5f01d9c1a2541219d2649d7dc57ac259b5
Reviewed-on: https://go-review.googlesource.com/c/dl/+/207097
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
1 file changed