Mutlipath deployment failing to create snapshots due to raw format

[Alexandr Kostrikov]

There is a failure at [0] when making a snapshot of environment

2016-10-16 19:37:39 - ERROR decorators.py:99 -- Error making the environment snapshot: ['libvirtError: unsupported configuration: internal snapshot for disk sda unsupported for storage type raw\n']

That is due to custom template yaml:
    volumes:
     - name: system
       capacity: !os_env NODE_VOLUME_SIZE, 55
       format: raw

At working environments there is such yaml:
    volumes:
     - name: system
       capacity: !os_env NODE_VOLUME_SIZE, 55
       format: qcow2

[0] https://product-ci.infra.mirantis.net/job/10.0.system_test.ubuntu.deploy_multipath/105/console

Additional info:
As there is no snapshot usage currently in multipath tests, it may be known issue.