From 74607d18c5355aed38b3354c64b307af96780e68 Mon Sep 17 00:00:00 2001
From: Anthony Martin <ality@pbrane.org>
Date: Mon, 16 Apr 2012 17:36:02 -0700
Subject: [PATCH] os: avoid panic when testing errors on Plan 9

R=golang-dev, bradfitz, akumar
CC=golang-dev
https://golang.org/cl/6017043
---
 src/pkg/os/error_plan9.go | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/pkg/os/error_plan9.go b/src/pkg/os/error_plan9.go
index 3c9dfb0b15..f083a2d1de 100644
--- a/src/pkg/os/error_plan9.go
+++ b/src/pkg/os/error_plan9.go
@@ -5,6 +5,9 @@
 package os
 
 func isExist(err error) bool {
+	if err == nil {
+		return false
+	}
 	if pe, ok := err.(*PathError); ok {
 		err = pe.Err
 	}
@@ -12,6 +15,9 @@ func isExist(err error) bool {
 }
 
 func isNotExist(err error) bool {
+	if err == nil {
+		return false
+	}
 	if pe, ok := err.(*PathError); ok {
 		err = pe.Err
 	}
@@ -19,6 +25,9 @@ func isNotExist(err error) bool {
 }
 
 func isPermission(err error) bool {
+	if err == nil {
+		return false
+	}
 	if pe, ok := err.(*PathError); ok {
 		err = pe.Err
 	}