cmd/go/internal/modload: allow 'go get' to use replaced versions
'go mod tidy' has been able to use replaced versions since CL 152739,
but 'go get' failed for many of the same paths. Now that we are
recommending 'go get' more aggressively due to #40728, we should make
that work too.
In the future, we might consider factoring out the new replacementRepo
type so that 'go list' can report the new versions as well.
For #41577
For #41416
For #37438
Updates #26241
Change-Id: I9140c556424b584fdd9bdd0a747842774664a7d8
Reviewed-on: https://go-review.googlesource.com/c/go/+/258220
Trust: Bryan C. Mills <bcmills@google.com>
Trust: Jay Conrod <jayconrod@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Michael Matloob <matloob@golang.org> Reviewed-by: Jay Conrod <jayconrod@google.com>