[REV] git packfile, avoid allocating in teeReader.ReadByte

pkg/builder/sources/git_test.go

@@ -36,7 +36,7 @@ func TestGitClone(t *testing.T) {
 		Branch:        "master",
 	}
 	//logger := event.GetManager().GetLogger("system")
-	res, err := GitClone(csi, "/tmp/rainbonddoc", nil, 1)
+	res, err := GitClone(csi, "/tmp/rainbonddoc2", nil, 1)
 	if err != nil {
 		t.Fatal(err)
 	}

vendor/gopkg.in/src-d/go-git.v4/plumbing/format/packfile/scanner.go

@@ -64,8 +64,8 @@ func NewScanner(r io.Reader) *Scanner {
 	crc := crc32.NewIEEE()
 	return &Scanner{
 		r: &teeReader{
-			newByteReadSeeker(seeker),
-			crc,
+			reader: newByteReadSeeker(seeker),
+			w:      crc,
 		},
 		crc:        crc,
 		IsSeekable: ok,
@@ -400,7 +400,8 @@ type reader interface {
 
 type teeReader struct {
 	reader
-	w hash.Hash32
+	w   hash.Hash32
+	buf [1]byte
 }
 
 func (r *teeReader) Read(p []byte) (n int, err error) {
@@ -416,7 +417,8 @@ func (r *teeReader) Read(p []byte) (n int, err error) {
 func (r *teeReader) ReadByte() (b byte, err error) {
 	b, err = r.reader.ReadByte()
 	if err == nil {
-		_, err := r.w.Write([]byte{b})
+		r.buf[0] = b
+		_, err := r.w.Write(r.buf[:])
 		if err != nil {
 			return 0, err
 		}