Various disk errors when offloading builds to a childhurd

[Tanguy LE CARROUR]

Hi Guix,

Since the Guix days, I’ve been experimenting with build offload
to a childhurd.

At first, (almost) everything was failing for a lack of free disk space.
So I change my childhurd’s configuration to:

```
(service hurd-vm-service-type
  (hurd-vm-configuration
    (os %hurd-vm-operating-system)
    (disk-size (* 20 (expt 2 30)))  ; 20GiB
    (memory-size 1024)))            ; 1GiB
```

It now builds packages, but fails randomly after some times.
When I inspect the VM using the VNC client, I see errors like:

```
ext2fs: BUG: unexpected fault on disk image (10, 0x8ffc000) in
[0xB8222000,0x18222000) eip 0x8052224 err 0xa
```

or:

```
ext2fs: disk-pager.c:109: fault_handler: Assertion ’err’ failed.
```

Any idea what might be going wrong?!

Regards,

-- 
Tanguy