I think "the flag" was a typo, and the word "after" was repetitive.

Change-Id: I81c034ca11a3a778ff1eb4b3af5b96bc525ab985
Reviewed-on: https://go-review.googlesource.com/10195Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>