properly format error messages for volume resizing

The error messages are tuples and not substituting variables.

Before:
$ openstack volume set vol1 --size 1
Failed to set volume size: (u'New size must be greater than %s GB', 2)

$ openstack volume set vol1 --size 1
Failed to set volume size: (u'Volume is in %s state, it must be available
before size can be extended', u'error')

After:
$ openstack volume set vol2 --size 3
Failed to set volume size: New size must be greater than 4 GB

$ openstack volume set vol2 --size 3
Failed to set volume size: Volume is in error state, it must be available
before size can be extended

Change-Id: Ide6e644b1c6d1c11a9dc2f3f53c1a1837380b8d5

Author: stevemar

openstackclient/volume/v2/volume.py

@@ -484,10 +484,11 @@ def take_action(self, parsed_args):
             try:
                 if volume.status != 'available':
                     msg = (_("Volume is in %s state, it must be available "
-                           "before size can be extended"), volume.status)
+                           "before size can be extended") % volume.status)
                     raise exceptions.CommandError(msg)
                 if parsed_args.size <= volume.size:
-                    msg = _("New size must be greater than %s GB"), volume.size
+                    msg = (_("New size must be greater than %s GB")
+                           % volume.size)
                     raise exceptions.CommandError(msg)
                 volume_client.volumes.extend(volume.id, parsed_args.size)
             except Exception as e: