How could I run this benchmarks in go mod environment?

[cupen]

This is what I am doing.

$ go version  
go version go1.12.4 linux/amd64
$ git clone https://github.com/json-iterator/go-benchmark
$ cd go-benchmark
$ go mod init github.com/json-iterator/go-benchmark
$ go mod tidy
$ go test ./...
go: finding github.com/json-iterator/go-benchmark/testobject latest
govendor/src/github.com/kardianos/govendor/context/context.go:18:2: use of internal package github.com/kardianos/govendor/internal/pathos not allowed
govendor/src/github.com/kardianos/govendor/context/resolve.go:17:2: use of internal package github.com/kardianos/govendor/internal/vfilepath not allowed
govendor/src/github.com/kardianos/govendor/context/context.go:19:2: use of internal package github.com/kardianos/govendor/internal/vos not allowed
govendor/src/github.com/kardianos/govendor/internal/vfilepath/walk.go:7:2: use of internal package github.com/kardianos/govendor/internal/vos not allowed
govendor/src/github.com/kardianos/govendor/run/filter.go:13:2: use of internal package github.com/kardianos/govendor/internal/pathos not allowed
govendor/src/github.com/kardianos/govendor/vcs/vcs.go:13:2: use of internal package github.com/kardianos/govendor/internal/pathos not allowed
govendor/src/github.com/kardianos/govendor/vcs/bzr.go:13:2: use of internal package github.com/kardianos/govendor/internal/vos not allowed