go.mod,vendor,backend: update coreos/etcd dependency to v3.4.9

etcd rewrote its import path from coreos/etcd to go.etcd.io/etcd/v3.
Changed the imports path in this commit.

This lets us remove the github.com/ugorji/go/codec dependency, which
was pinned to a fairly old version. The net change is a loss of 30,000
lines of code in the vendor directory. (I first noticed this problem
because the outdated go/codec dependency was causing a dependency
failure when I tried to put Terraform and another project in the same
vendor directory.)

One oddity is that the commit shows up in go.mod as 3.3.0 but is
actually after 3.4.9, there's some discussion of that (and how to
resolve it) here.
etcd-io/etcd#12068 (comment)

backend/remote-state/etcdv2/backend.go

@@ -6,11 +6,11 @@ import (
 	"context"
 	"strings"
 
-	etcdapi "github.com/coreos/etcd/client"
 	"github.com/hashicorp/terraform/backend"
 	"github.com/hashicorp/terraform/helper/schema"
 	"github.com/hashicorp/terraform/state"
 	"github.com/hashicorp/terraform/state/remote"
+	etcdapi "go.etcd.io/etcd/v3/client"
 )
 
 func New() backend.Backend {

backend/remote-state/etcdv2/client.go

@@ -5,8 +5,8 @@ import (
 	"crypto/md5"
 	"fmt"
 
-	etcdapi "github.com/coreos/etcd/client"
 	"github.com/hashicorp/terraform/state/remote"
+	etcdapi "go.etcd.io/etcd/v3/client"
 )
 
 // EtcdClient is a remote client that stores data in etcd.

backend/remote-state/etcdv3/backend.go

@@ -3,10 +3,10 @@ package etcd
 import (
 	"context"
 
-	etcdv3 "github.com/coreos/etcd/clientv3"
-	"github.com/coreos/etcd/pkg/transport"
 	"github.com/hashicorp/terraform/backend"
 	"github.com/hashicorp/terraform/helper/schema"
+	etcdv3 "go.etcd.io/etcd/v3/clientv3"
+	"go.etcd.io/etcd/v3/pkg/transport"
 )
 
 const (

backend/remote-state/etcdv3/backend_state.go

@@ -6,12 +6,11 @@ import (
 	"sort"
 	"strings"
 
-	etcdv3 "github.com/coreos/etcd/clientv3"
-
 	"github.com/hashicorp/terraform/backend"
 	"github.com/hashicorp/terraform/state"
 	"github.com/hashicorp/terraform/state/remote"
 	"github.com/hashicorp/terraform/states"
+	etcdv3 "go.etcd.io/etcd/v3/clientv3"
 )
 
 func (b *Backend) Workspaces() ([]string, error) {

backend/remote-state/etcdv3/backend_test.go

@@ -9,8 +9,8 @@ import (
 	"testing"
 	"time"
 
-	etcdv3 "github.com/coreos/etcd/clientv3"
 	"github.com/hashicorp/terraform/backend"
+	etcdv3 "go.etcd.io/etcd/v3/clientv3"
 )
 
 var (

backend/remote-state/etcdv3/client.go

@@ -8,11 +8,11 @@ import (
 	"sync"
 	"time"
 
-	etcdv3 "github.com/coreos/etcd/clientv3"
-	etcdv3sync "github.com/coreos/etcd/clientv3/concurrency"
 	"github.com/hashicorp/go-multierror"
 	"github.com/hashicorp/terraform/state"
 	"github.com/hashicorp/terraform/state/remote"
+	etcdv3 "go.etcd.io/etcd/v3/clientv3"
+	etcdv3sync "go.etcd.io/etcd/v3/clientv3/concurrency"
 )
 
 const (

go.mod

@@ -24,21 +24,14 @@ require (
 	github.com/bgentry/speakeasy v0.1.0
 	github.com/blang/semver v3.5.1+incompatible
 	github.com/bmatcuk/doublestar v1.1.5
-	github.com/boltdb/bolt v1.3.1 // indirect
 	github.com/chzyer/logex v1.1.10 // indirect
 	github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e
 	github.com/chzyer/test v0.0.0-20180213035817-a1ea475d72b1 // indirect
-	github.com/coreos/bbolt v1.3.0 // indirect
-	github.com/coreos/etcd v3.3.10+incompatible
-	github.com/coreos/go-semver v0.2.0 // indirect
-	github.com/coreos/go-systemd v0.0.0-20181012123002-c6f51f82210d // indirect
-	github.com/coreos/pkg v0.0.0-20180928190104-399ea9e2e55f // indirect
 	github.com/davecgh/go-spew v1.1.1
 	github.com/dylanmei/iso8601 v0.1.0 // indirect
 	github.com/dylanmei/winrmtest v0.0.0-20190225150635-99b7fe2fddf1
 	github.com/go-test/deep v1.0.3
 	github.com/gofrs/uuid v3.3.0+incompatible // indirect
-	github.com/golang/groupcache v0.0.0-20180513044358-24b0969c4cb7 // indirect
 	github.com/golang/mock v1.3.1
 	github.com/golang/protobuf v1.3.4
 	github.com/golang/snappy v0.0.0-20180518054509-2e65f85255db // indirect
@@ -47,10 +40,6 @@ require (
 	github.com/gophercloud/gophercloud v0.10.1-0.20200424014253-c3bfe50899e5
 	github.com/gophercloud/utils v0.0.0-20200423144003-7c72efc7435d
 	github.com/gopherjs/gopherjs v0.0.0-20181017120253-0766667cb4d1 // indirect
-	github.com/gorilla/websocket v1.4.0 // indirect
-	github.com/grpc-ecosystem/go-grpc-middleware v1.0.0 // indirect
-	github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0 // indirect
-	github.com/grpc-ecosystem/grpc-gateway v1.8.5 // indirect
 	github.com/hashicorp/aws-sdk-go-base v0.5.0
 	github.com/hashicorp/consul v0.0.0-20171026175957-610f3c86a089
 	github.com/hashicorp/errwrap v1.0.0
@@ -80,7 +69,6 @@ require (
 	github.com/hashicorp/yamux v0.0.0-20181012175058-2f1d1f20f75d // indirect
 	github.com/imdario/mergo v0.3.9 // indirect
 	github.com/jmespath/go-jmespath v0.3.0
-	github.com/jonboulle/clockwork v0.1.0 // indirect
 	github.com/joyent/triton-go v0.0.0-20180313100802-d8f9c0314926
 	github.com/jtolds/gls v4.2.1+incompatible // indirect
 	github.com/kardianos/osext v0.0.0-20190222173326-2bc1f35cddc0
@@ -112,26 +100,19 @@ require (
 	github.com/pkg/browser v0.0.0-20180916011732-0a3d74bf9ce4
 	github.com/pkg/errors v0.9.1
 	github.com/posener/complete v1.2.1
-	github.com/prometheus/client_golang v0.9.3-0.20190127221311-3c4408c8b829 // indirect
 	github.com/sean-/seed v0.0.0-20170313163322-e2103e2c3529 // indirect
 	github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d // indirect
 	github.com/smartystreets/goconvey v0.0.0-20180222194500-ef6db91d284a // indirect
-	github.com/soheilhy/cmux v0.1.4 // indirect
 	github.com/spf13/afero v1.2.2
 	github.com/tencentcloud/tencentcloud-sdk-go v3.0.82+incompatible
 	github.com/tencentyun/cos-go-sdk-v5 v0.0.0-20190808065407-f07404cefc8c
-	github.com/tmc/grpc-websocket-proxy v0.0.0-20171017195756-830351dc03c6 // indirect
 	github.com/tombuildsstuff/giovanni v0.10.1
-	github.com/ugorji/go v0.0.0-20180813092308-00b869d2f4a5 // indirect
 	github.com/vmihailenco/msgpack v4.0.1+incompatible // indirect
 	github.com/xanzy/ssh-agent v0.2.1
-	github.com/xiang90/probing v0.0.0-20160813154853-07dd2e8dfe18 // indirect
 	github.com/xlab/treeprint v0.0.0-20161029104018-1d6e34225557
 	github.com/zclconf/go-cty v1.5.1
 	github.com/zclconf/go-cty-yaml v1.0.2
-	go.uber.org/atomic v1.3.2 // indirect
-	go.uber.org/multierr v1.1.0 // indirect
-	go.uber.org/zap v1.9.1 // indirect
+	go.etcd.io/etcd/v3 v3.3.0-rc.0.0.20200710174459-07461ecc8c03
 	golang.org/x/crypto v0.0.0-20200604202706-70a84ac30bf9
 	golang.org/x/mod v0.2.0
 	golang.org/x/net v0.0.0-20200602114024-627f9648deb9