GitLab

Fixes the docs to correctly match the implementation
and also adds a test locking-in the behavior to prevent
any accidental future regressions on the docs.

Fixes #33545

Change-Id: I6fdac6048cce8ac99beaa2db0dfc81d0dccc10f1
Reviewed-on: https://go-review.googlesource.com/c/go/+/200798


Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>