[zaphod-v0.3.1]:[bug] Fix error in destroyvm

SYNOPSIS
[modified]m42/zaphod.py: Fix typo in destroyvm.

DETAILS
Incorrect use of an already used variable name combined with
a typo causes incorrect destruction of HD images inside destroy
VMs.
[zaphod-v0.4]: [merge] Branch release into main.

SYNOPSIS
[modified]m42/zaphod.py: Apply bugfix 5cefb2 in the proper place in v0.4 code.

DETAILS
Code has moved around in v0.4. So this merge applies the fixes from v0.3.1
intelligently into the correct place in v0.4 code.