Update src-d/go-git to v4.13.0 (#7688)

* update gopkg.in/src-d/go-git.v4 v4.13.0

* mod tidy

* vendor

vendor/github.com/kevinburke/ssh_config/lexer.go

@@ -1,22 +1,22 @@
 package ssh_config
 
 import (
-	"io"
-
-	buffruneio "github.com/pelletier/go-buffruneio"
+	"bytes"
 )
 
 // Define state functions
 type sshLexStateFn func() sshLexStateFn
 
 type sshLexer struct {
-	input         *buffruneio.Reader // Textual source
-	buffer        []rune             // Runes composing the current token
+	inputIdx int
+	input    []rune // Textual source
+
+	buffer        []rune // Runes composing the current token
 	tokens        chan token
-	line          uint32
-	col           uint16
-	endbufferLine uint32
-	endbufferCol  uint16
+	line          int
+	col           int
+	endbufferLine int
+	endbufferCol  int
 }
 
 func (s *sshLexer) lexComment(previousState sshLexStateFn) sshLexStateFn {
@@ -114,16 +114,14 @@ func (s *sshLexer) lexRvalue() sshLexStateFn {
 }
 
 func (s *sshLexer) read() rune {
-	r, _, err := s.input.ReadRune()
-	if err != nil {
-		panic(err)
-	}
+	r := s.peek()
 	if r == '\n' {
 		s.endbufferLine++
 		s.endbufferCol = 1
 	} else {
 		s.endbufferCol++
 	}
+	s.inputIdx++
 	return r
 }
 
@@ -197,21 +195,22 @@ func (s *sshLexer) emitWithValue(t tokenType, value string) {
 }
 
 func (s *sshLexer) peek() rune {
-	r, _, err := s.input.ReadRune()
-	if err != nil {
-		panic(err)
+	if s.inputIdx >= len(s.input) {
+		return eof
 	}
-	s.input.UnreadRune()
+
+	r := s.input[s.inputIdx]
 	return r
 }
 
 func (s *sshLexer) follow(next string) bool {
+	inputIdx := s.inputIdx
 	for _, expectedRune := range next {
-		r, _, err := s.input.ReadRune()
-		defer s.input.UnreadRune()
-		if err != nil {
-			panic(err)
+		if inputIdx >= len(s.input) {
+			return false
 		}
+		r := s.input[inputIdx]
+		inputIdx++
 		if expectedRune != r {
 			return false
 		}
@@ -226,10 +225,10 @@ func (s *sshLexer) run() {
 	close(s.tokens)
 }
 
-func lexSSH(input io.Reader) chan token {
-	bufferedInput := buffruneio.NewReader(input)
+func lexSSH(input []byte) chan token {
+	runes := bytes.Runes(input)
 	l := &sshLexer{
-		input:         bufferedInput,
+		input:         runes,
 		tokens:        make(chan token),
 		line:          1,
 		col:           1,