subtle bug

buggy.go

package main

import (
        "bufio"
        "fmt"
        "os"
)

// test it:
// eval printf '...............%s\\n' `printf '{#..$}%.0s' {1..16}` | go run buggy.go

func main() {
        scanner := bufio.NewScanner(os.Stdin)
        allLines := [][]byte{}
        linecount := 0

        scanner.Scan()
        lineBytes := scanner.Bytes()
        allLines = append(allLines, lineBytes)
        firstLine := string(lineBytes)

        for scanner.Scan() {
                linecount += 1
                lineBytes = scanner.Bytes()
                allLines = append(allLines, lineBytes)
                line := string(allLines[0])
                if line != firstLine {
                        fmt.Printf("Whaaat???? Line %d\n", linecount)
                        os.Exit(1)
                }
        }
}