Don't panic on two ^D

Here's what happens if you type Ctrl-D twice.

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init: 2023/05/25 17:05:37 Waiting for orphaned children
init: 2023/05/25 17:05:37 All commands exited
init: 2023/05/25 17:05:37 Syncing filesystems
init: 2023/05/25 17:05:37 Exiting...
Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000000
Kernel Offset: 0x11e00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000000 ]---
QEMU: Terminated