cmd/go: incompatible module version not detected by 'go run' or 'go build'

What version of Go are you using (go version)?

Does this issue reproduce with the latest release?

yes

What operating system and processor architecture are you using (go env)?

What did you do?

Create the following go.mod file:

module test
  
go 1.13

require k8s.io/client-go v12.0.0+incompatible

Create the following main.go file:

package main
  
import (
        "fmt"

        "k8s.io/client-go/pkg/version"
)

func main() { fmt.Println(version.Get()) }

What did you expect to see?

The toolchain should fail all interactions with k8s.io/client-go because of the combination of the go.mod file at the v12.0.0 tag:

[user@localhost test]$ go get k8s.io/client-go@v12.0.0
go: finding k8s.io v12.0.0
go: finding k8s.io/client-go v12.0.0
go: finding k8s.io/client-go v12.0.0
go get k8s.io/client-go@v12.0.0: k8s.io/client-go@v12.0.0: invalid version: module contains a go.mod file, so major version must be compatible: should be v0 or v1, not v12
[user@localhost test]$ go run .
go: finding k8s.io/client-go v12.0.0+incompatible
go: finding k8s.io/client-go v12.0.0+incompatible
go list -m: k8s.io/client-go@v12.0.0+incompatible: invalid version: +incompatible suffix not allowed: module contains a go.mod file, so semantic import versioning is required
[user@localhost test]$ go build
go: finding k8s.io/client-go v12.0.0+incompatible
go: finding k8s.io/client-go v12.0.0+incompatible
go list -m: k8s.io/client-go@v12.0.0+incompatible: invalid version: +incompatible suffix not allowed: module contains a go.mod file, so semantic import versioning is required
[user@localhost test]$ go doc k8s.io/client-go/pkg/version
go: finding k8s.io/client-go v12.0.0+incompatible
go: finding k8s.io/client-go v12.0.0+incompatible
go list -m: k8s.io/client-go@v12.0.0+incompatible: invalid version: +incompatible suffix not allowed: module contains a go.mod file, so semantic import versioning is required

What did you see instead?

All parts of the toolchain I tested appear to re-find the problematic module on every invocation, however go get fails (as above), go doc warns, and both go run and go build succeed:

[user@localhost test]$ go run .
go: finding k8s.io/client-go v12.0.0+incompatible
go: finding k8s.io/client-go v12.0.0+incompatible
v0.0.0-master+$Format:%h$
[user@localhost test]$ go build
go: finding k8s.io/client-go v12.0.0+incompatible
go: finding k8s.io/client-go v12.0.0+incompatible
[user@localhost test]$ ./test 
v0.0.0-master+$Format:%h$
[user@localhost test]$ go doc k8s.io/client-go/pkg/version
go: finding k8s.io/client-go v12.0.0+incompatible
go: finding k8s.io/client-go v12.0.0+incompatible
go list -m: k8s.io/client-go@v12.0.0+incompatible: invalid version: +incompatible suffix not allowed: module contains a go.mod file, so semantic import versioning is required
package version // import "k8s.io/client-go/pkg/version"

Package version supplies version information collected at build time to
kubernetes components.

func Get() apimachineryversion.Info