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 (