This reverts CL 162337.

Reason for revert: this introduces a regression

Fixes #33538
Updates #18929

Change-Id: Ib2320a840c6d3ec7912e8f414e933d04fbf11ab4
Reviewed-on: https://go-review.googlesource.com/c/go/+/189379Reviewed-by: Robert Griesemer <gri@golang.org>