cmd/go: 'go get' does not add missing hash to go.sum when ziphash file missing from cache [1.16 backport] #44812
Description
@jayconrod requested issue #44749 to be considered for backport to the next 1.16 minor release.
@gopherbot Please backport to 1.16. It's a pre-existing issue, but it's much more likely to be observed because of the switch to
-mod=readonlyby default.