diff --git a/vendor/cmd/go/internal/modcmd/mod.go b/vendor/cmd/go/internal/modcmd/mod.go
index 8e0e51a..aa7a11a 100644
--- a/vendor/cmd/go/internal/modcmd/mod.go
+++ b/vendor/cmd/go/internal/modcmd/mod.go
@@ -59,6 +59,9 @@
 
 The -replace=old@v=>new@w and -dropreplace=old@v flags
 add and drop a replacement of the given module path and version pair.
+If the @v in old@v is omitted, the replacement applies to all versions
+with the old module path. If the @v in new@v is omitted, the
+new path should be a directory on the local system, not a module path.
 Note that -replace overrides any existing replacements for old@v.
 
 These editing flags (-require, -droprequire, -exclude, -dropexclude,
@@ -252,6 +255,7 @@
 			edit(modFile)
 		}
 	}
+	modFile.SortBlocks()
 	modload.WriteGoMod() // write back syntactic changes
 
 	// Semantic edits.
@@ -397,14 +401,16 @@
 		base.Fatalf("go mod: -replace=%s: need old@v=>new[@v] (missing =>)", arg)
 	}
 	old, new := strings.TrimSpace(arg[:i]), strings.TrimSpace(arg[i+2:])
+	var oldPath, oldVersion string
 	if i = strings.Index(old, "@"); i < 0 {
-		base.Fatalf("go mod: -replace=%s: need old@v=>new[@v] (missing @ in old@v)", arg)
+		oldPath = old
+	} else {
+		oldPath, oldVersion = strings.TrimSpace(old[:i]), strings.TrimSpace(old[i+1:])
 	}
-	oldPath, oldVersion := strings.TrimSpace(old[:i]), strings.TrimSpace(old[i+1:])
 	if err := module.CheckPath(oldPath); err != nil {
 		base.Fatalf("go mod: -replace=%s: invalid old path: %v", arg, err)
 	}
-	if modfile.MustQuote(oldVersion) {
+	if oldPath != old && modfile.MustQuote(oldVersion) {
 		base.Fatalf("go mod: -replace=%s: invalid old version %q", arg, oldVersion)
 	}
 	var newPath, newVersion string
diff --git a/vendor/cmd/go/internal/modfile/rule.go b/vendor/cmd/go/internal/modfile/rule.go
index 1f15c97..80a3bbc 100644
--- a/vendor/cmd/go/internal/modfile/rule.go
+++ b/vendor/cmd/go/internal/modfile/rule.go
@@ -189,8 +189,12 @@
 			})
 		}
 	case "replace":
-		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)
+		arrow := 2
+		if len(args) >= 2 && args[1] == "=>" {
+			arrow = 1
+		}
+		if len(args) < arrow+2 || len(args) > arrow+3 || args[arrow] != "=>" {
+			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])
@@ -198,28 +202,31 @@
 			fmt.Fprintf(errs, "%s:%d: invalid quoted string: %v\n", f.Syntax.Name, line.Start.Line, err)
 			return
 		}
-		old := args[1]
-		v, err := parseVersion(s, &args[1], fix)
-		if err != nil {
-			fmt.Fprintf(errs, "%s:%d: invalid module version %v: %v\n", f.Syntax.Name, line.Start.Line, old, err)
-			return
-		}
 		v1, err := moduleMajorVersion(s)
 		if err != nil {
 			fmt.Fprintf(errs, "%s:%d: %v\n", f.Syntax.Name, line.Start.Line, err)
 			return
 		}
-		if v2 := semver.Major(v); v1 != v2 && (v1 != "v1" || v2 != "v0") {
-			fmt.Fprintf(errs, "%s:%d: invalid module: %s should be %s, not %s (%s)\n", f.Syntax.Name, line.Start.Line, s, v1, v2, v)
-			return
+		var v string
+		if arrow == 2 {
+			old := args[1]
+			v, err = parseVersion(s, &args[1], fix)
+			if err != nil {
+				fmt.Fprintf(errs, "%s:%d: invalid module version %v: %v\n", f.Syntax.Name, line.Start.Line, old, err)
+				return
+			}
+			if v2 := semver.Major(v); v1 != v2 && (v1 != "v1" || v2 != "v0") {
+				fmt.Fprintf(errs, "%s:%d: invalid module: %s should be %s, not %s (%s)\n", f.Syntax.Name, line.Start.Line, s, v1, v2, v)
+				return
+			}
 		}
-		ns, err := parseString(&args[3])
+		ns, err := parseString(&args[arrow+1])
 		if err != nil {
 			fmt.Fprintf(errs, "%s:%d: invalid quoted string: %v\n", f.Syntax.Name, line.Start.Line, err)
 			return
 		}
 		nv := ""
-		if len(args) == 4 {
+		if len(args) == arrow+2 {
 			if !IsDirectoryPath(ns) {
 				fmt.Fprintf(errs, "%s:%d: replacement module without version must be directory path (rooted or starting with ./ or ../)", f.Syntax.Name, line.Start.Line)
 				return
@@ -229,9 +236,9 @@
 				return
 			}
 		}
-		if len(args) == 5 {
-			old := args[4]
-			nv, err = parseVersion(ns, &args[4], fix)
+		if len(args) == arrow+3 {
+			old := args[arrow+1]
+			nv, err = parseVersion(ns, &args[arrow+2], fix)
 			if err != nil {
 				fmt.Fprintf(errs, "%s:%d: invalid module version %v: %v\n", f.Syntax.Name, line.Start.Line, old, err)
 				return
@@ -241,7 +248,6 @@
 				return
 			}
 		}
-		// TODO: More sanity checks about directories vs module paths.
 		f.Replace = append(f.Replace, &Replace{
 			Old:    module.Version{Path: s, Version: v},
 			New:    module.Version{Path: ns, Version: nv},
@@ -554,14 +560,18 @@
 	need := true
 	old := module.Version{Path: oldPath, Version: oldVers}
 	new := module.Version{Path: newPath, Version: newVers}
-	tokens := []string{"replace", AutoQuote(oldPath), oldVers, "=>", AutoQuote(newPath)}
+	tokens := []string{"replace", AutoQuote(oldPath)}
+	if oldVers != "" {
+		tokens = append(tokens, oldVers)
+	}
+	tokens = append(tokens, "=>", AutoQuote(newPath))
 	if newVers != "" {
 		tokens = append(tokens, newVers)
 	}
 
 	var hint *Line
 	for _, r := range f.Replace {
-		if r.Old == old {
+		if r.Old.Path == oldPath && (oldVers == "" || r.Old.Version == oldVers) {
 			if need {
 				// Found replacement for old; update to use new.
 				r.New = new
diff --git a/vendor/cmd/go/internal/modfile/testdata/replace2.golden b/vendor/cmd/go/internal/modfile/testdata/replace2.golden
index 1d18a3b..e1d9c72 100644
--- a/vendor/cmd/go/internal/modfile/testdata/replace2.golden
+++ b/vendor/cmd/go/internal/modfile/testdata/replace2.golden
@@ -5,4 +5,6 @@
 	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
+
+	xyz => my/other/xyz v1.5.4
 )
diff --git a/vendor/cmd/go/internal/modfile/testdata/replace2.in b/vendor/cmd/go/internal/modfile/testdata/replace2.in
index 78c4669..7864698 100644
--- a/vendor/cmd/go/internal/modfile/testdata/replace2.in
+++ b/vendor/cmd/go/internal/modfile/testdata/replace2.in
@@ -5,4 +5,6 @@
 	"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
+
+	xyz => my/other/xyz v1.5.4
 )
diff --git a/vendor/cmd/go/internal/modload/load.go b/vendor/cmd/go/internal/modload/load.go
index 2528db7..5333c65 100644
--- a/vendor/cmd/go/internal/modload/load.go
+++ b/vendor/cmd/go/internal/modload/load.go
@@ -646,7 +646,7 @@
 	}
 	var found *modfile.Replace
 	for _, r := range modFile.Replace {
-		if r.Old == mod {
+		if r.Old.Path == mod.Path && (r.Old.Version == "" || r.Old.Version == mod.Version) {
 			found = r // keep going
 		}
 	}
diff --git a/vendor/cmd/go/mod_test.go b/vendor/cmd/go/mod_test.go
index dbff0ca..26e6ea1 100644
--- a/vendor/cmd/go/mod_test.go
+++ b/vendor/cmd/go/mod_test.go
@@ -208,6 +208,7 @@
 	tg.must(ioutil.WriteFile(tg.path("w/w.go"), []byte("package w\n"), 0666))
 
 	mustHaveGoMod := func(text string) {
+		t.Helper()
 		data, err := ioutil.ReadFile(tg.path("go.mod"))
 		tg.must(err)
 		if string(data) != text {
@@ -305,6 +306,33 @@
 		t.Fatalf("go mod -json mismatch:\nhave:<<<\n%s>>>\nwant:<<<\n%s\n", have, want)
 	}
 
+	tg.run("mod",
+		"-replace=x.1@v1.3.0=>y.1/v2@v2.3.5",
+		"-replace=x.1@v1.4.0=>y.1/v2@v2.3.5",
+	)
+	mustHaveGoMod(`module x.x/y/z
+
+exclude x.1 v1.2.0
+
+replace (
+	x.1 v1.3.0 => y.1/v2 v2.3.5
+	x.1 v1.4.0 => y.1/v2 v2.3.5
+)
+
+require x.3 v1.99.0
+`)
+	tg.run("mod",
+		"-replace=x.1=>y.1/v2@v2.3.6",
+	)
+	mustHaveGoMod(`module x.x/y/z
+
+exclude x.1 v1.2.0
+
+replace x.1 => y.1/v2 v2.3.6
+
+require x.3 v1.99.0
+`)
+
 	tg.run("mod", "-packages")
 	want = `x.x/y/z
 x.x/y/z/w
@@ -324,7 +352,7 @@
 
 exclude x.1 v1.2.0
 
-replace x.1 v1.4.0 => ../z
+replace x.1 => y.1/v2 v2.3.6
 
 require x.3 v1.99.0
 `)
@@ -696,8 +724,7 @@
 replace y.1 v1.0.0 => ../y
 replace z.1 v1.1.0 => ../z
 replace z.1 v1.2.0 => ../z
-replace w.1 v1.1.0 => ../w
-replace w.1 v1.2.0 => ../w
+replace w.1 => ../w
 `)
 	write("m/m.go", `
 package m