Creating submodules in a single commit

script.txt

$ mkdir -p /home/gopher/scratchpad/submodulestest
$ cd /home/gopher/scratchpad/submodulestest
$ git init -q
$ git remote add origin https://github.com/go-modules-by-example-staging/submodulestest
$ go mod init github.com/go-modules-by-example-staging/submodulestest
go: creating new go.mod: module github.com/go-modules-by-example-staging/submodulestest
$ mkdir b
$ cd b
$ cat <<EOD >b.go
package b
const Name = "Gopher"
EOD
$ go mod init github.com/go-modules-by-example-staging/submodulestest/b
go: creating new go.mod: module github.com/go-modules-by-example-staging/submodulestest/b
$ go test
?       github.com/go-modules-by-example-staging/submodulestest/b       [no test files]
$ mkdir a
$ cd a
$ cat <<EOD >a.go
package main
import (
        "github.com/go-modules-by-example-staging/submodulestest/b"
        "fmt"
)
const Name = b.Name
func main() {
        fmt.Println(Name)
}
EOD
$ go mod init github.com/go-modules-by-example-staging/submodulestest/a
go: creating new go.mod: module github.com/go-modules-by-example-staging/submodulestest/a
$ go mod edit -require=github.com/go-modules-by-example-staging/submodulestest/b@v0.1.1 -replace=github.com/go-modules-by-example-staging/submodulestest/b=../b
$ go run .
go: finding github.com/go-modules-by-example-staging/submodulestest/b v0.1.1
Gopher
$ go list -m github.com/go-modules-by-example-staging/submodulestest/b
go: finding github.com/go-modules-by-example-staging/submodulestest/b v0.1.1
github.com/go-modules-by-example-staging/submodulestest/b v0.1.1 => ../b
$ git add -A
$ git commit -q -am 'Initial commit'
$ git push -q
remote:
remote: Create a pull request for 'master' on GitHub by visiting:
remote:      https://github.com/go-modules-by-example-staging/submodulestest/pull/new/master
remote:
$ git tag b/v0.1.1
$ git push -q origin b/v0.1.1
$ git tag a/v1.0.0
$ git push -q origin a/v1.0.0
$ cd $(mktemp -d)
$ export GOBIN=$PWD/.bin
$ go mod init example.com/blah
go: creating new go.mod: module example.com/blah
$ go get github.com/go-modules-by-example-staging/submodulestest/a@v1.0.0
go: finding github.com/go-modules-by-example-staging/submodulestest/a v1.0.0
go: finding github.com/go-modules-by-example-staging/submodulestest/b v0.1.1
go: downloading github.com/go-modules-by-example-staging/submodulestest/a v1.0.0
go: downloading github.com/go-modules-by-example-staging/submodulestest/b v0.1.1
$ $GOBIN/a
Gopher
$ go version
go version go1.11.2 linux/amd64