Setup-storage failure for LVM on wheezy

[Nicolas Courtel]

Hello,

Trying to install a wheezy host using FAI 4.0~beta3+experimental7, I 
have some troubles with setup-storage; the current disk partitioning is 
the following:

sda1 = primary partition for /boot
sda2 = primary partition for lvm volumes = vg0/root, vg0/usr, ...

The new partitioning should be the same, without preserving anything 
because of alignment issues. This is what happens:

[...]
Executing: wipefs -a /dev/sda1
Executing: vgchange -a n vg0
Executing: wipefs -a vg0/var
Command had non-zero exit code

There seems to be 2 problems:
- wipefs argument should be /dev/vg0/var
- vgchange -a n should not be called before wipefs, as it prevents it 
from seeing the partition

I have tweaked Commands.pm so that it does not fail in this case, but a 
clean fix might be useful in a future version of setup-storage.

-- 
Nicolas