## Description of problem:

After failed 'hosted-engine --upgrade-appliance', rollback does not remove failed attempt

## Version-Release number of selected component (if applicable):

ovirt-hosted-engine-setup-2.0.2.2-2.el7ev.noarch

## How reproducible:
1/1 for me (iscsi storage)

## Steps to Reproduce:
1. do failed upgrade (3.6 to 4.0) - 120GB for HE storage domain
2. successfully roll back
3. try and update again

## Actual results:

2nd attempt to update fails with this error:

2016-10-04 16:03:41 ERROR otopi.plugins.gr_he_upgradeappliance.engine.misc misc._check_sd_and_disk_space:223 On the hosted-engine storage domain there is not enough available space to create a new disk for backup purposes and eventually extend the current disk to fit the new appliance: required 50GiB - available 13GiB. Please extend the hosted-engine storage domain.
2016-10-04 16:03:41 DEBUG otopi.context context._executeMethod:142 method exception
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/otopi/context.py", line 132, in _executeMethod
    method['method']()
  File "/usr/share/ovirt-hosted-engine-setup/scripts/../plugins/gr-he-upgradeappliance/engine/misc.py", line 227, in _check_sd_and_disk_space
    'Not enough free space on the hosted-engine storage domain'
RuntimeError: Not enough free space on the hosted-engine storage domain
2016-10-04 16:03:41 ERROR otopi.context context._executeMethod:151 Failed to execute stage 'Environment customization': Not enough free space on the hosted-engine storage domain


## Expected results:

It would be good hosted-engine removed the previous failed attempt.  I don't think it's reasonable to keep extending the HE storage domain each time there is a failed attempt.  At the least, output the unused lv's so that they can be deleted.

## Additional info:

I was able to figure out the lvm to delete, but I wouldn't expect a regular user to be able to do this.  There's also a huge potential here to remove the wrong lv...