diff --git a/go.mod b/go.mod

index 13f7c66bb..e0615affa 100644

--- a/go.mod

+++ b/go.mod

@@ -77,7 +77,6 @@ require (

 	golang.org/x/oauth2 v0.0.0-20190319182350-c85d3e98c914

 	golang.org/x/sync v0.0.0-20190227155943-e225da77a7e6

 	golang.org/x/sys v0.0.0-20190415081028-16da32be82c5 // indirect

-	golang.org/x/xerrors v0.0.0-20190410155217-1f06c39b4373

 	gopkg.in/alexcesaro/quotedprintable.v3 v3.0.0-20150716171945-2caba252f4dc // indirect

 	gopkg.in/asn1-ber.v1 v1.0.0-20181015200546-f715ec2f112d // indirect

 	gopkg.in/bufio.v1 v1.0.0-20140618132640-567b2bfa514e // indirect

diff --git a/vendor/golang.org/x/xerrors/adaptor_go1_12.go b/vendor/golang.org/x/xerrors/adaptor.go

similarity index 99%

rename from vendor/golang.org/x/xerrors/adaptor_go1_12.go

rename to vendor/golang.org/x/xerrors/adaptor.go

index 6b9f2f0c7..4317f2483 100644

--- a/vendor/golang.org/x/xerrors/adaptor_go1_12.go

+++ b/vendor/golang.org/x/xerrors/adaptor.go

@@ -2,8 +2,6 @@

 // Use of this source code is governed by a BSD-style

 // license that can be found in the LICENSE file.

-// +build !go1.13

-

 package xerrors

 import (

diff --git a/vendor/golang.org/x/xerrors/adaptor_go1_13.go b/vendor/golang.org/x/xerrors/adaptor_go1_13.go

deleted file mode 100644

index 57f519dc5..000000000

--- a/vendor/golang.org/x/xerrors/adaptor_go1_13.go

+++ /dev/null

@@ -1,55 +0,0 @@

-// Copyright 2018 The Go Authors. All rights reserved.

-// Use of this source code is governed by a BSD-style

-// license that can be found in the LICENSE file.

-

-// +build go1.13

-

-package xerrors

-

-import (

-	"errors"

-	"fmt"

-	"strconv"

-)

-

-// A Frame contains part of a call stack.

-type Frame = errors.Frame

-

-// Caller returns a Frame that describes a frame on the caller's stack.

-// The argument skip is the number of frames to skip over.

-// Caller(0) returns the frame for the caller of Caller.

-var Caller func(skip int) Frame = errors.Caller

-

-// FormatError calls the FormatError method of f with an errors.Printer

-// configured according to s and verb, and writes the result to s.

-func FormatError(f Formatter, s fmt.State, verb rune) {

-	// Assuming this function is only called from the Format method, and given

-	// that FormatError takes precedence over Format, it cannot be called from

-	// any package that supports errors.Formatter. It is therefore safe to

-	// disregard that State may be a specific printer implementation and use one

-	// of our choice instead.

-

-	width, okW := s.Width()

-	prec, okP := s.Precision()

-

-	// Construct format string from State s.

-	format := []byte{'%'}

-	if s.Flag('-') {

-		format = append(format, '-')

-	}

-	if s.Flag('+') {

-		format = append(format, '+')

-	}

-	if s.Flag(' ') {

-		format = append(format, ' ')

-	}

-	if okW {

-		format = strconv.AppendInt(format, int64(width), 10)

-	}

-	if okP {

-		format = append(format, '.')

-		format = strconv.AppendInt(format, int64(prec), 10)

-	}

-	format = append(format, string(verb)...)

-	fmt.Fprintf(s, string(format), f)

-}

diff --git a/vendor/golang.org/x/xerrors/format_go1_12.go b/vendor/golang.org/x/xerrors/format.go

similarity index 98%

rename from vendor/golang.org/x/xerrors/format_go1_12.go

rename to vendor/golang.org/x/xerrors/format.go

index ba856feab..1bc9c26b9 100644

--- a/vendor/golang.org/x/xerrors/format_go1_12.go

+++ b/vendor/golang.org/x/xerrors/format.go

@@ -2,8 +2,6 @@

 // Use of this source code is governed by a BSD-style

 // license that can be found in the LICENSE file.

-// +build !go1.13

-

 package xerrors

 // A Formatter formats error messages.

diff --git a/vendor/golang.org/x/xerrors/format_go1_13.go b/vendor/golang.org/x/xerrors/format_go1_13.go

deleted file mode 100644

index 95c65968b..000000000

--- a/vendor/golang.org/x/xerrors/format_go1_13.go

+++ /dev/null

@@ -1,19 +0,0 @@

-// Copyright 2018 The Go Authors. All rights reserved.

-// Use of this source code is governed by a BSD-style

-// license that can be found in the LICENSE file.

-

-// +build go1.13

-

-package xerrors

-

-import "errors"

-

-// A Formatter formats error messages.

-type Formatter = errors.Formatter

-

-// A Printer formats error messages.

-//

-// The most common implementation of Printer is the one provided by package fmt

-// during Printf (as of Go 1.13). Localization packages such as golang.org/x/text/message

-// typically provide their own implementations.

-type Printer = errors.Printer

diff --git a/vendor/golang.org/x/xerrors/frame_go1_12.go b/vendor/golang.org/x/xerrors/frame.go

similarity index 98%

rename from vendor/golang.org/x/xerrors/frame_go1_12.go

rename to vendor/golang.org/x/xerrors/frame.go

index 6740f7fa6..0de628ec5 100644

--- a/vendor/golang.org/x/xerrors/frame_go1_12.go

+++ b/vendor/golang.org/x/xerrors/frame.go

@@ -2,8 +2,6 @@

 // Use of this source code is governed by a BSD-style

 // license that can be found in the LICENSE file.

-// +build !go1.13

-

 package xerrors

 import (