This is better than parsing the default output.
Also, change the start progress message, since it ends up duplicating
the title in the message that the user sees.
Change-Id: I3540d30c7976c6be0722531b2e258341081e0b72
Reviewed-on: https://go-review.googlesource.com/c/tools/+/251920
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>