NoneType error on mountpoint check while adding vpool

[matthiasdeblock]

Openvstorage 2.9.12-1

Error while extending vpool on a storagerouter which has a disk with mountpoint 'None'.

{'available': 475111882752L, 'usable': True, 'in_use': False, 'mountpoint': None, 'ssd': True, 'guid': '616b0c83-50a1-4d1c-bd15-fcfabb558ecf', 'storagerouter_guid': '89651e05-b2e3-4510-a15e-73aeaefb2e0d', 'size': 475111882752L}
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-3-9e72acdacf70> in <module>()
----> 1 test.mountpoint_checker()

<ipython-input-1-dec905ea51f6> in mountpoint_checker(cls)
    105                     for part in part_info:
    106                         print part
--> 107                         if not client.is_mounted(part['mountpoint']) and part['mountpoint'] != DiskPartition.VIRTUAL_STORAGE_LOCATION:
    108                             error_messages.append('Mount point {0} is not mounted'.format(part['mountpoint']))
    109         return error_messages

/usr/lib/python2.7/dist-packages/ovs_extensions/generic/sshclient.pyc in is_mounted(self, path)
    795         :rtype: bool
    796         """
--> 797         path = path.rstrip('/')
    798         if self.is_local is True:
    799             return os.path.ismount(path)

AttributeError: 'NoneType' object has no attribute 'rstrip'