Dear Maintainer,

The new unmkinitramfs written in C has a regression. In case the output
pipe of lsinitramfs is closed prematurely, you might get an error
message printed:

```
unmkinitramfs: cpio failed
```

I saw this failure in the qemu-busybox autopkgtest on Ubuntu, but were
able to reproduce it on Debian. Example:

```
$ lsinitramfs /boot/initrd.img-6.12.32-amd64 | grep -wq chroot
unmkinitramfs: cpio failed
```