A recent change (silently) broke our go1.12 presubmit, because we don't
yet have a means to surface this breakage. Coming soon: a 'gopls CI'
custom Gerrit label.
In the meantime, fix the build.
Change-Id: I31f5b7512403fdbd8869652cd4b8e77b084c8534
Reviewed-on: https://go-review.googlesource.com/c/tools/+/253517
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>