From 353fd1014c78b3b76fb5233f477677e0333e5f1a Mon Sep 17 00:00:00 2001
From: Rob Pike <r@golang.org>
Date: Fri, 7 Jan 2011 14:41:33 -0800
Subject: [PATCH] bytes.Buffer: Fix bug in UnreadByte. Error check was
 inverted.

Fixes #1396.

R=rsc, adg
CC=golang-dev
https://golang.org/cl/3851042
---
 src/pkg/bytes/buffer.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/pkg/bytes/buffer.go b/src/pkg/bytes/buffer.go
index 55d3133868..2574b4f432 100644
--- a/src/pkg/bytes/buffer.go
+++ b/src/pkg/bytes/buffer.go
@@ -291,7 +291,7 @@ func (b *Buffer) UnreadRune() os.Error {
 // read operation.  If write has happened since the last read, UnreadByte
 // returns an error.
 func (b *Buffer) UnreadByte() os.Error {
-	if b.lastRead == opReadRune || b.lastRead == opRead {
+	if b.lastRead != opReadRune && b.lastRead != opRead {
 		return os.ErrorString("bytes.Buffer: UnreadByte: previous operation was not a read")
 	}
 	b.lastRead = opInvalid
-- 
2.48.1