Bug#1031183: grub-installer: postinst fails if efivarfs cannot be mounted

[Arnaud Rebillout <arnaudr@kali.org>]

Hello,

I'm testing a Kali Linux mini.iso, in a BIOS virtual machine. Kali uses 
the grub-installer package from Debian, no change and it's up-to-date.

The postinst still fails at this point. The error can be reproduced from 
the console:

  mkdir -p /target/sys/firmware/efi/efivars
  mkdir: can't create directory '/target/sys/firmware/efi': Operation 
not permitted

I suppose the mkdir call must also be allowed to fail when fstype is 
efivarfs (following the same logic that is already used for mount).

Do you want me to submit a patch?

NB: the issue only affects a BIOS VM. If I boot a UEFI VM, everything 
works fine.

Thanks

--
Arnaud Rebillout / OffSec / Kali Linux Developer