go modules:the pkg uses two different module paths

[唐彦昭]

<!-- Please answer these questions before submitting your issue. Thanks! -->

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

<pre>

$ go version

go version go1.12.5 linux/amd64

</pre>

### Does this issue reproduce with the latest release?

Yes

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

<details><summary><code>go env</code> Output</summary><br><pre>

$ go env

GOARCH="amd64"

GOBIN=""

GOCACHE="/data/home/***/.cache/go-build"

GOEXE=""

GOFLAGS=""

GOHOSTARCH="amd64"

GOHOSTOS="linux"

GOOS="linux"

GOPATH="/data/home/***/go"

GOPROXY=""

GORACE=""

GOROOT="/usr/local/go"

GOTMPDIR=""

GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"

GCCGO="gccgo"

CC="gcc"

CXX="g++"

CGO_ENABLED="1"

GOMOD="/data/home/***/***/***/go.mod"

CGO_CFLAGS="-g -O2"

CGO_CPPFLAGS=""

CGO_CXXFLAGS="-g -O2"

CGO_FFLAGS="-g -O2"

CGO_LDFLAGS="-g -O2"

PKG_CONFIG="pkg-config"

GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build015182643=/tmp/go-build -gno-record-gcc-switches"

</pre></details>

### What did you do?

<!--

If possible, provide a recipe for reproducing the error.

A complete runnable program is good.

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-->

go.mod:

replace (

        bou.ke/monkey => github.com/bouk/monkey v1.0.0

        go.uber.org/multierr => github.com/uber-go/multierr v1.1.0

        go.uber.org/zap => github.com/uber-go/zap v1.9.1

        golang.org/x/crypto => github.com/golang/crypto v0.0.0-20190422183909-d864b10871cd

        golang.org/x/lint => github.com/golang/lint v0.0.0-20190409202823-959b441ac422

        golang.org/x/net => github.com/golang/net v0.0.0-20190420063019-afa5a82059c6

        golang.org/x/sync => github.com/golang/sync v0.0.0-20190423024810-112230192c58

        golang.org/x/sys => github.com/golang/sys v0.0.0-20190422165155-953cdadca894

        golang.org/x/text => github.com/golang/text v0.3.0

        golang.org/x/tools => github.com/golang/tools v0.0.0-20190422233926-fe54fb35175b

        google.golang.org/appengine => github.com/golang/appengine v1.6.0

        google.golang.org/genproto => github.com/google/go-genproto v0.0.0-20190418145605-e7d98fc518a7

        google.golang.org/grpc => github.com/grpc/grpc-go v1.20.1

        gopkg.in/alecthomas/kingpin.v2 => github.com/alecthomas/kingpin v2.2.6+incompatible

        gopkg.in/check.v1 => github.com/go-check/check v0.0.0-20180628173108-788fd7840127

        gopkg.in/fsnotify.v1 => github.com/fsnotify/fsnotify v1.4.8-0.20190312181446-1485a34d5d57

        gopkg.in/go-playground/assert.v1 => github.com/go-playground/assert v1.2.1

        gopkg.in/go-playground/validator.v8 => github.com/go-playground/validator v8.18.2+incompatible

        gopkg.in/ini.v1 => github.com/go-ini/ini v1.42.0

        gopkg.in/tomb.v1 => github.com/go-tomb/tomb v0.0.0-20141024135613-dd632973f1e7

        gopkg.in/yaml.v2 => github.com/go-yaml/yaml v0.0.0-20181115110504-51d6538a90f8

)

And then

$ vend

$ go build -mod=vendor

go: github.com/golang/appe...@v1.6.0 used for two different module paths (github.com/golang/appengine and google.golang.org/appengine)

go: github.com/go-ini/i...@v1.42.0 used for two different module paths (github.com/go-ini/ini and gopkg.in/ini.v1)

### What did you expect to see?

compile success

### What did you see instead?

compile failed