go module @latest found but does not contain package

I'm trying to make use of go module for the first time. What exactly the following error message is telling me?

module github.com/mkideal/cli@latest found (v0.2.2), but does not contain package github.com/mkideal/cli
module github.com/mkideal/cli@latest found (v0.2.2), but does not contain package github.com/mkideal/cli/ext

It happens during go build, whereas go get is just fine:

$ go get -v github.com/mkideal/cli
go: github.com/mkideal/cli upgrade => v0.2.2

but not go get -v ./..., which gave me the same error as above. My proxy setting looks OK:

$ go env | grep GOPROXY
GOPROXY="https://proxy.golang.org,direct"

Is it a problem of the go module/package I'm trying to use, or my own code's problem? -- I took a look at https://github.com/mkideal/cli/blob/master/go.mod and it seems fine to me.

See the following update for details.

How can I overcome the situation? (I'm getting the same error message for my own repo as well)

UPDATE:

Here is the full log how I'm getting the above error:

prepare /tmp/015-file from https://github.com/mkideal/cli/blob/master/_examples/015-file
do go mod init
then go build

Now the details:

$ cd /tmp/015-file

$ GO111MODULE=on

$ go mod init github.com/mkideal/cli/015-file
go: creating new go.mod: module github.com/mkideal/cli/015-file

$ cat go.mod 
module github.com/mkideal/cli/015-file

go 1.14

$ go build
go: finding module for package github.com/mkideal/cli
go: finding module for package github.com/mkideal/cli/ext
main.go:6:2: module github.com/mkideal/cli@latest found (v0.2.2), but does not contain package github.com/mkideal/cli
main.go:7:2: module github.com/mkideal/cli@latest found (v0.2.2), but does not contain package github.com/mkideal/cli/ext

$ go get -v github.com/mkideal/cli
go: github.com/mkideal/cli upgrade => v0.2.2

$ go get -v ./...
go: finding module for package github.com/mkideal/cli
go: finding module for package github.com/mkideal/cli/ext
go: finding module for package github.com/mkideal/cli
go: finding module for package github.com/mkideal/cli/ext
main.go:6:2: module github.com/mkideal/cli@latest found (v0.2.2), but does not contain package github.com/mkideal/cli
main.go:7:2: module github.com/mkideal/cli@latest found (v0.2.2), but does not contain package github.com/mkideal/cli/ext

$ go version
go version go1.14.1 linux/amd64

Solution

Cleaning up Golang caches should do the job:

go clean -cache
go clean -modcache

For more info on how this command works, use go help clean. If you have similar problems with your test environment, run go clean -testcache.