handles multiple exchange commands differently from GNU (pattern space  truncation)

Rust (incorrect - pattern space truncated)
```
  $ echo -e "line1\nline2\nline3" | cargo run -p sed -- '2x;3x'
  line1
  line2
  # Exit code: 0

```

  GNU (correct)
 ```
 $ echo -e "line1\nline2\nline3" | /usr/bin/sed '2x;3x'
  line1

  line2
  # Exit code: 0

```