gofmt -r 'α[β:len(α)] -> α[β:]' -w src/cmd src/pkg

R=r, gri
CC=golang-dev
https://golang.org/cl/156115

src/pkg/syscall/errstr.go

@@ -17,7 +17,7 @@ func str(val int) string {	// do it here rather than with fmt to avoid dependenc
 		val /= 10;
 	}
 	buf[i] = byte(val + '0');
-	return string(buf[i:len(buf)]);
+	return string(buf[i:]);
 }
 
 func Errstr(errno int) string {