Parsing StatusMessage XML with StatusMessage gives a different result to the original

[danielsamuels]

If you provide a list of acceptable destinations in the status detail of a StatusMessage object, then transform the StatusMessage to XML and re-parse it, the value of status.status_detail will be structured differently in the parsed object.

Here's a very straight-forward reproduction case:

import libtaxii.messages_11 as tm11
from libtaxii.constants import *

status_message = tm11.StatusMessage(
    message_id=tm11.generate_message_id(),
    in_response_to='0',
    status_type=ST_DESTINATION_COLLECTION_ERROR,
    status_detail={
        SD_ACCEPTABLE_DESTINATION: [
            'foo',
            'bar',
            'baz',
        ]
    }
)

print status_message.status_detail
# {'ACCEPTABLE_DESTINATION': ['foo', 'bar', 'baz']}

xml = status_message.to_xml()
"""
<taxii_11:Status_Message xmlns:taxii="http://taxii.mitre.org/messages/taxii_xml_binding-1" xmlns:taxii_11="http://taxii.mitre.org/messages/taxii_xml_binding-1.1" xmlns:tdq="http://taxii.mitre.org/query/taxii_default_query-1" message_id="4183586003553703942" in_response_to="0" status_type="DESTINATION_COLLECTION_ERROR">
    <taxii_11:Status_Detail>
        <taxii_11:Detail name="ACCEPTABLE_DESTINATION">foo</taxii_11:Detail>
        <taxii_11:Detail name="ACCEPTABLE_DESTINATION">bar</taxii_11:Detail>
        <taxii_11:Detail name="ACCEPTABLE_DESTINATION">baz</taxii_11:Detail>
    </taxii_11:Status_Detail>
</taxii_11:Status_Message>
"""

print tm11.StatusMessage.from_xml(xml).status_detail
# {'ACCEPTABLE_DESTINATION': [['foo', 'bar'], 'baz']}

If you specify only two destinations then the output is as expected:

{'ACCEPTABLE_DESTINATION': ['foo', 'bar']}

However, as you add more and more destinations they become nested deeper and deeper:

{'ACCEPTABLE_DESTINATION': [[[[['foo', 'bar'], 'baz'], 'x'], 'y'], 'z']}

The XML appears to be well-formed, so I imagine there's an issue in the .from_xml() method.

[danielsamuels]

@gtback I've opened PR #231 to fix this issue as well as add a test for the bug. Would you be able to take a look please?

[emmanvg]

@danielsamuels sorry for getting back to you so late. I will take a look at this.