diff --git a/vendor/cmd/go/internal/modconv/modconv.go b/vendor/cmd/go/internal/modconv/modconv.go
index 478e76f..b689b52 100644
--- a/vendor/cmd/go/internal/modconv/modconv.go
+++ b/vendor/cmd/go/internal/modconv/modconv.go
@@ -22,4 +22,4 @@
 // for dependencies before caching them.
 // In case of bugs in the converter, if we bump this version number,
 // then all the cached copies will be ignored.
-const Prefix = "//vgo 0.0.3\n"
+const Prefix = "//vgo 0.0.4\n"
diff --git a/vendor/cmd/go/internal/modfetch/coderepo_test.go b/vendor/cmd/go/internal/modfetch/coderepo_test.go
index e23a575..ff25516 100644
--- a/vendor/cmd/go/internal/modfetch/coderepo_test.go
+++ b/vendor/cmd/go/internal/modfetch/coderepo_test.go
@@ -198,7 +198,7 @@
 		name:    "0f30252985809011f026b5a2d5cf456e021623da",
 		short:   "0f3025298580",
 		time:    time.Date(2018, 2, 20, 2, 47, 20, 0, time.UTC),
-		gomod:   "//vgo 0.0.3\n\nmodule \"go.googlesource.com/scratch\"\n",
+		gomod:   "//vgo 0.0.4\n\nmodule go.googlesource.com/scratch\n",
 	},
 	{
 		path:    "go.googlesource.com/scratch/rsc",
@@ -287,7 +287,7 @@
 		name:    "d670f9405373e636a5a2765eea47fac0c9bc91a4",
 		short:   "d670f9405373",
 		time:    time.Date(2018, 1, 9, 11, 43, 31, 0, time.UTC),
-		gomod:   "//vgo 0.0.3\n\nmodule \"gopkg.in/yaml.v2\"\n",
+		gomod:   "//vgo 0.0.4\n\nmodule gopkg.in/yaml.v2\n",
 	},
 	{
 		path:    "gopkg.in/check.v1",
@@ -296,7 +296,7 @@
 		name:    "20d25e2804050c1cd24a7eea1e7a6447dd0e74ec",
 		short:   "20d25e280405",
 		time:    time.Date(2016, 12, 8, 18, 13, 25, 0, time.UTC),
-		gomod:   "//vgo 0.0.3\n\nmodule \"gopkg.in/check.v1\"\n",
+		gomod:   "//vgo 0.0.4\n\nmodule gopkg.in/check.v1\n",
 	},
 }
 
diff --git a/vendor/cmd/go/internal/modfetch/convert_test.go b/vendor/cmd/go/internal/modfetch/convert_test.go
index fd69b94..ad9f690 100644
--- a/vendor/cmd/go/internal/modfetch/convert_test.go
+++ b/vendor/cmd/go/internal/modfetch/convert_test.go
@@ -27,23 +27,23 @@
 		{
 			// Gopkg.lock parsing.
 			"github.com/golang/dep", "v0.4.0",
-			`module "github.com/golang/dep"
+			`module github.com/golang/dep
 
 			require (
-				"github.com/Masterminds/semver" v0.0.0-20170726230514-a93e51b5a57e
-				"github.com/Masterminds/vcs" v1.11.1
-				"github.com/armon/go-radix" v0.0.0-20160115234725-4239b77079c7
-				"github.com/boltdb/bolt" v1.3.1
-				"github.com/go-yaml/yaml" v0.0.0-20170407172122-cd8b52f8269e
-				"github.com/golang/protobuf" v0.0.0-20170901042739-5afd06f9d81a
-				"github.com/jmank88/nuts" v0.3.0
-				"github.com/nightlyone/lockfile" v0.0.0-20170707060451-e83dc5e7bba0
-				"github.com/pelletier/go-toml" v0.0.0-20171218135716-b8b5e7696574
-				"github.com/pkg/errors" v0.8.0
-				"github.com/sdboyer/constext" v0.0.0-20170321163424-836a14457353
-				"golang.org/x/net" v0.0.0-20170828231752-66aacef3dd8a
-				"golang.org/x/sync" v0.0.0-20170517211232-f52d1811a629
-				"golang.org/x/sys" v0.0.0-20170830134202-bb24a47a89ea
+				github.com/Masterminds/semver v0.0.0-20170726230514-a93e51b5a57e
+				github.com/Masterminds/vcs v1.11.1
+				github.com/armon/go-radix v0.0.0-20160115234725-4239b77079c7
+				github.com/boltdb/bolt v1.3.1
+				github.com/go-yaml/yaml v0.0.0-20170407172122-cd8b52f8269e
+				github.com/golang/protobuf v0.0.0-20170901042739-5afd06f9d81a
+				github.com/jmank88/nuts v0.3.0
+				github.com/nightlyone/lockfile v0.0.0-20170707060451-e83dc5e7bba0
+				github.com/pelletier/go-toml v0.0.0-20171218135716-b8b5e7696574
+				github.com/pkg/errors v0.8.0
+				github.com/sdboyer/constext v0.0.0-20170321163424-836a14457353
+				golang.org/x/net v0.0.0-20170828231752-66aacef3dd8a
+				golang.org/x/sync v0.0.0-20170517211232-f52d1811a629
+				golang.org/x/sys v0.0.0-20170830134202-bb24a47a89ea
 			)`,
 		},
 
@@ -53,25 +53,25 @@
 			// Godeps.json parsing.
 			// TODO: Should v2.0.0 work here too?
 			"github.com/docker/distribution", "v0.0.0-20150410205453-85de3967aa93",
-			`module "github.com/docker/distribution"
+			`module github.com/docker/distribution
 			
 			require (
-    				"github.com/AdRoll/goamz" v0.0.0-20150130162828-d3664b76d905
-				"github.com/bugsnag/bugsnag-go" v0.0.0-20141110184014-b1d153021fcd
-				"github.com/bugsnag/osext" v0.0.0-20130617224835-0dd3f918b21b
-				"github.com/bugsnag/panicwrap" v0.0.0-20141110184334-e5f9854865b9
-				"github.com/docker/libtrust" v0.0.0-20150114040149-fa567046d9b1
-				"github.com/garyburd/redigo" v0.0.0-20150301180006-535138d7bcd7
-				"github.com/gorilla/context" v0.0.0-20140604161150-14f550f51af5
-				"github.com/gorilla/handlers" v0.0.0-20140825150757-0e84b7d810c1
-				"github.com/gorilla/mux" v0.0.0-20140926153814-e444e69cbd2e
-				"github.com/jlhawn/go-crypto" v0.0.0-20150401213827-cd738dde20f0
-				"github.com/yvasiyarov/go-metrics" v0.0.0-20140926110328-57bccd1ccd43
-				"github.com/yvasiyarov/gorelic" v0.0.0-20141212073537-a9bba5b9ab50
-				"github.com/yvasiyarov/newrelic_platform_go" v0.0.0-20140908184405-b21fdbd4370f
-				"golang.org/x/net" v0.0.0-20150202051010-1dfe7915deaf
-				"gopkg.in/check.v1" v0.0.0-20141024133853-64131543e789
-				"gopkg.in/yaml.v2" v0.0.0-20150116202057-bef53efd0c76
+    				github.com/AdRoll/goamz v0.0.0-20150130162828-d3664b76d905
+				github.com/bugsnag/bugsnag-go v0.0.0-20141110184014-b1d153021fcd
+				github.com/bugsnag/osext v0.0.0-20130617224835-0dd3f918b21b
+				github.com/bugsnag/panicwrap v0.0.0-20141110184334-e5f9854865b9
+				github.com/docker/libtrust v0.0.0-20150114040149-fa567046d9b1
+				github.com/garyburd/redigo v0.0.0-20150301180006-535138d7bcd7
+				github.com/gorilla/context v0.0.0-20140604161150-14f550f51af5
+				github.com/gorilla/handlers v0.0.0-20140825150757-0e84b7d810c1
+				github.com/gorilla/mux v0.0.0-20140926153814-e444e69cbd2e
+				github.com/jlhawn/go-crypto v0.0.0-20150401213827-cd738dde20f0
+				github.com/yvasiyarov/go-metrics v0.0.0-20140926110328-57bccd1ccd43
+				github.com/yvasiyarov/gorelic v0.0.0-20141212073537-a9bba5b9ab50
+				github.com/yvasiyarov/newrelic_platform_go v0.0.0-20140908184405-b21fdbd4370f
+				golang.org/x/net v0.0.0-20150202051010-1dfe7915deaf
+				gopkg.in/check.v1 v0.0.0-20141024133853-64131543e789
+				gopkg.in/yaml.v2 v0.0.0-20150116202057-bef53efd0c76
 			)`,
 		},
 	}
diff --git a/vendor/cmd/go/internal/modfile/read.go b/vendor/cmd/go/internal/modfile/read.go
index 7fdf827..a0c88d6 100644
--- a/vendor/cmd/go/internal/modfile/read.go
+++ b/vendor/cmd/go/internal/modfile/read.go
@@ -238,6 +238,18 @@
 	return int(r)
 }
 
+// peekPrefix reports whether the remaining input begins with the given prefix.
+func (in *input) peekPrefix(prefix string) bool {
+	// This is like bytes.HasPrefix(in.remaining, []byte(prefix))
+	// but without the allocation of the []byte copy of prefix.
+	for i := 0; i < len(prefix); i++ {
+		if i >= len(in.remaining) || in.remaining[i] != prefix[i] {
+			return false
+		}
+	}
+	return true
+}
+
 // readRune consumes and returns the next rune in the input.
 func (in *input) readRune() int {
 	if len(in.remaining) == 0 {
@@ -302,7 +314,7 @@
 		}
 
 		// Comment runs to end of line.
-		if c == '/' {
+		if in.peekPrefix("//") {
 			in.startToken(sym)
 
 			// Is this comment the only thing on its line?
@@ -311,13 +323,7 @@
 			i := bytes.LastIndex(in.complete[:in.pos.Byte], []byte("\n"))
 			suffix := len(bytes.TrimSpace(in.complete[i+1:in.pos.Byte])) > 0
 			in.readRune()
-			c = in.peekRune()
-			if c == '*' {
-				in.Error(fmt.Sprintf("mod files must use // comments (not /* */ comments)"))
-			}
-			if c != '/' {
-				in.Error(fmt.Sprintf("unexpected input character %#q", c))
-			}
+			in.readRune()
 
 			// Consume comment.
 			for len(in.remaining) > 0 && in.readRune() != '\n' {
@@ -344,6 +350,10 @@
 			return _EOL
 		}
 
+		if in.peekPrefix("/*") {
+			in.Error(fmt.Sprintf("mod files must use // comments (not /* */ comments)"))
+		}
+
 		// Found non-space non-comment.
 		break
 	}
@@ -406,6 +416,12 @@
 
 	// Scan over identifier.
 	for isIdent(in.peekRune()) {
+		if in.peekPrefix("//") {
+			break
+		}
+		if in.peekPrefix("/*") {
+			in.Error(fmt.Sprintf("mod files must use // comments (not /* */ comments)"))
+		}
 		in.readRune()
 	}
 	return _IDENT
@@ -414,7 +430,7 @@
 // isIdent reports whether c is an identifier rune.
 // We treat nearly all runes as identifier runes.
 func isIdent(c int) bool {
-	return c != 0 && !unicode.IsSpace(rune(c)) && c != '/' && c != '(' && c != ')' && c != '"' && c != '`'
+	return c != 0 && !unicode.IsSpace(rune(c))
 }
 
 // Comment assignment.
diff --git a/vendor/cmd/go/internal/modfile/read_test.go b/vendor/cmd/go/internal/modfile/read_test.go
index 9879603..3c73528 100644
--- a/vendor/cmd/go/internal/modfile/read_test.go
+++ b/vendor/cmd/go/internal/modfile/read_test.go
@@ -97,10 +97,13 @@
 
 		eq := eqchecker{file: base}
 		if err := eq.check(f, f2); err != nil {
-			t.Errorf("not equal: %v", err)
+			t.Errorf("not equal (parse/Format/parse): %v", err)
 		}
 
 		pf1, err := Parse(base, data, nil)
+		if err != nil && base == "testdata/replace2.in" {
+			t.Errorf("should parse %v: %v", base, err)
+		}
 		if err == nil {
 			pf2, err := Parse(base, ndata, nil)
 			if err != nil {
@@ -109,8 +112,23 @@
 			}
 			eq := eqchecker{file: base}
 			if err := eq.check(pf1, pf2); err != nil {
-				t.Errorf("not equal: %v", err)
+				t.Errorf("not equal (parse/Format/Parse): %v", err)
 			}
+
+			ndata2, err := pf1.Format()
+			if err != nil {
+				t.Errorf("reformat: %v", err)
+			}
+			pf3, err := Parse(base, ndata2, nil)
+			if err != nil {
+				t.Errorf("Parsing reformatted2: %v", err)
+				continue
+			}
+			eq = eqchecker{file: base}
+			if err := eq.check(pf1, pf3); err != nil {
+				t.Errorf("not equal (Parse/Format/Parse): %v", err)
+			}
+			ndata = ndata2
 		}
 
 		if strings.HasSuffix(out, ".in") {
diff --git a/vendor/cmd/go/internal/modfile/rule.go b/vendor/cmd/go/internal/modfile/rule.go
index 8a69f10..11fa36c 100644
--- a/vendor/cmd/go/internal/modfile/rule.go
+++ b/vendor/cmd/go/internal/modfile/rule.go
@@ -12,6 +12,7 @@
 	"sort"
 	"strconv"
 	"strings"
+	"unicode"
 
 	"cmd/go/internal/module"
 	"cmd/go/internal/semver"
@@ -56,7 +57,7 @@
 		f.Syntax = new(FileSyntax)
 	}
 	f.Syntax.Stmt = append(f.Syntax.Stmt, &Line{
-		Token: []string{"module", strconv.Quote(path)},
+		Token: []string{"module", AutoQuote(path)},
 	})
 }
 
@@ -120,9 +121,9 @@
 			return
 		}
 		f.Module = new(Module)
-		if len(args) != 1 || !isString(args[0]) {
+		if len(args) != 1 {
 
-			fmt.Fprintf(errs, "%s:%d: usage: module \"module/path\" [version]\n", f.Syntax.Name, line.Start.Line)
+			fmt.Fprintf(errs, "%s:%d: usage: module module/path [version]\n", f.Syntax.Name, line.Start.Line)
 			return
 		}
 		s, err := parseString(&args[0])
@@ -132,8 +133,8 @@
 		}
 		f.Module.Mod = module.Version{Path: s}
 	case "require", "exclude":
-		if len(args) != 2 || !isString(args[0]) || isString(args[1]) {
-			fmt.Fprintf(errs, "%s:%d: usage: %s \"module/path\" v1.2.3\n", f.Syntax.Name, line.Start.Line, verb)
+		if len(args) != 2 {
+			fmt.Fprintf(errs, "%s:%d: usage: %s module/path v1.2.3\n", f.Syntax.Name, line.Start.Line, verb)
 			return
 		}
 		s, err := parseString(&args[0])
@@ -168,8 +169,8 @@
 			})
 		}
 	case "replace":
-		if len(args) < 4 || len(args) > 5 || !isString(args[0]) || isString(args[1]) || args[2] != "=>" || !isString(args[3]) || len(args) == 5 && isString(args[4]) {
-			fmt.Fprintf(errs, "%s:%d: usage: %s \"module/path\" v1.2.3 -> \"other/module\" v1.4\n\t or %s \"module/path\" v1.2.3 -> \"../local/directory\"", f.Syntax.Name, line.Start.Line, verb, verb)
+		if len(args) < 4 || len(args) > 5 || args[2] != "=>" {
+			fmt.Fprintf(errs, "%s:%d: usage: %s module/path v1.2.3 => other/module v1.4\n\t or %s module/path v1.2.3 => ../local/directory", f.Syntax.Name, line.Start.Line, verb, verb)
 			return
 		}
 		s, err := parseString(&args[0])
@@ -237,21 +238,46 @@
 		len(ns) >= 2 && ('A' <= ns[0] && ns[0] <= 'Z' || 'a' <= ns[0] && ns[0] <= 'z') && ns[1] == ':'
 }
 
-func isString(s string) bool {
-	return s != "" && s[0] == '"'
+func mustQuote(t string) bool {
+	for _, r := range t {
+		if !unicode.IsPrint(r) || r == ' ' || r == '"' || r == '\'' || r == '`' {
+			return true
+		}
+	}
+	return t == "" || strings.Contains(t, "//") || strings.Contains(t, "/*")
+}
+
+// AutoQuote returns s or, if quoting is required for s to appear in a go.mod,
+// the quotation of s.
+func AutoQuote(s string) string {
+	if mustQuote(s) {
+		return strconv.Quote(s)
+	}
+	return s
 }
 
 func parseString(s *string) (string, error) {
-	t, err := strconv.Unquote(*s)
-	if err != nil {
-		return "", err
+	t := *s
+	if strings.HasPrefix(t, `"`) {
+		var err error
+		if t, err = strconv.Unquote(t); err != nil {
+			return "", err
+		}
+	} else if strings.ContainsAny(t, "\"'`") {
+		// Other quotes are reserved both for possible future expansion
+		// and to avoid confusion. For example if someone types 'x'
+		// we want that to be a syntax error and not a literal x in literal quotation marks.
+		return "", fmt.Errorf("unquoted string cannot contain quote")
 	}
-	*s = strconv.Quote(t)
+	*s = AutoQuote(t)
 	return t, nil
 }
 
 func parseVersion(path string, s *string, fix VersionFixer) (string, error) {
-	t := *s
+	t, err := parseString(s)
+	if err != nil {
+		return "", err
+	}
 	if fix != nil {
 		var err error
 		t, err = fix(path, t)
@@ -309,14 +335,14 @@
 		switch stmt := stmt.(type) {
 		case *LineBlock:
 			if len(stmt.Token) > 0 && stmt.Token[0] == "require" {
-				syntax = &Line{Token: []string{strconv.Quote(path), vers}}
+				syntax = &Line{Token: []string{AutoQuote(path), vers}}
 				stmt.Line = append(stmt.Line, syntax)
 				goto End
 			}
 		case *Line:
 			if len(stmt.Token) > 0 && stmt.Token[0] == "require" {
 				stmt.Token = stmt.Token[1:]
-				syntax = &Line{Token: []string{strconv.Quote(path), vers}}
+				syntax = &Line{Token: []string{AutoQuote(path), vers}}
 				x.Syntax.Stmt[i] = &LineBlock{
 					Comments: stmt.Comments,
 					Token:    []string{"require"},
@@ -330,7 +356,7 @@
 		}
 	}
 
-	syntax = &Line{Token: []string{"require", strconv.Quote(path), vers}}
+	syntax = &Line{Token: []string{"require", AutoQuote(path), vers}}
 	x.Syntax.Stmt = append(x.Syntax.Stmt, syntax)
 
 End:
diff --git a/vendor/cmd/go/internal/modfile/testdata/module.golden b/vendor/cmd/go/internal/modfile/testdata/module.golden
index 08f3836..78ba943 100644
--- a/vendor/cmd/go/internal/modfile/testdata/module.golden
+++ b/vendor/cmd/go/internal/modfile/testdata/module.golden
@@ -1 +1 @@
-module "abc"
+module abc
diff --git a/vendor/cmd/go/internal/modfile/testdata/replace.golden b/vendor/cmd/go/internal/modfile/testdata/replace.golden
index 6852499..5d6abcf 100644
--- a/vendor/cmd/go/internal/modfile/testdata/replace.golden
+++ b/vendor/cmd/go/internal/modfile/testdata/replace.golden
@@ -1,5 +1,5 @@
-module "abc"
+module abc
 
-replace "xyz" v1.2.3 => "/tmp/z"
+replace xyz v1.2.3 => /tmp/z
 
-replace "xyz" v1.3.4 => "my/xyz" v1.3.4-me
+replace xyz v1.3.4 => my/xyz v1.3.4-me
diff --git a/vendor/cmd/go/internal/modfile/testdata/replace2.golden b/vendor/cmd/go/internal/modfile/testdata/replace2.golden
index e80962e..1d18a3b 100644
--- a/vendor/cmd/go/internal/modfile/testdata/replace2.golden
+++ b/vendor/cmd/go/internal/modfile/testdata/replace2.golden
@@ -1,6 +1,8 @@
-module "abc"
+module abc
 
 replace (
-	"xyz" v1.2.3 => "/tmp/z"
-	"xyz" v1.3.4 => "my/xyz" v1.3.4-me
+	xyz v1.2.3 => /tmp/z
+	xyz v1.3.4 => my/xyz v1.3.4-me
+	xyz v1.4.5 => "/tmp/my dir"
+	xyz v1.5.6 => my/xyz v1.5.6
 )
diff --git a/vendor/cmd/go/internal/modfile/testdata/replace2.in b/vendor/cmd/go/internal/modfile/testdata/replace2.in
index e80962e..78c4669 100644
--- a/vendor/cmd/go/internal/modfile/testdata/replace2.in
+++ b/vendor/cmd/go/internal/modfile/testdata/replace2.in
@@ -2,5 +2,7 @@
 
 replace (
 	"xyz" v1.2.3 => "/tmp/z"
-	"xyz" v1.3.4 => "my/xyz" v1.3.4-me
+	"xyz" v1.3.4 => "my/xyz" "v1.3.4-me"
+	xyz "v1.4.5" => "/tmp/my dir"
+	xyz v1.5.6 => my/xyz v1.5.6
 )