[release-branch.go1.13] cmd/go: suppress more errors in package-to-module loading
In CL 197059, I suppressed errors if the target package was already found.
However, that does not cover the case of passing a '/v2' module path to
'go get' when the module does not contain a package at its root.
This CL is a minimal fix for that case, intended to be backportable to 1.13.
(Longer term, I intend to rework the version-validation check to treat
all mismatched paths as ErrNotExist.)
Updates #34746
Fixes #34747
Change-Id: Ia963c2ea00fae424812b8f46a4d6c2c668252147
Reviewed-on: https://go-review.googlesource.com/c/go/+/199839
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>
(cherry picked from commit
421d35cf69f4a18edf96004ba99c01e629a0f79f)
Reviewed-on: https://go-review.googlesource.com/c/go/+/199997