[generateDS] too many values to unpack

Trying to use generateDS to generate golang API results in the following traceback:

root@dpdk-builder:~/contrail-generateDS# ./generateDS.py -f -o ~/output -g golang-api /opt/contrail/controller/src/schema/vnc_cfg.xsd
WARNING:ifmap_model:route-target not found in xml schema
WARNING:ifmap_model:bgp-router not found in xml schema
WARNING:ifmap_model:routing-policy not found in xml schema
WARNING:ifmap_model:customer-attachment not found in xml schema
WARNING:ifmap_model:provider-attachment not found in xml schema
WARNING:ifmap_model:routing-instance not found in xml schema
WARNING:ifmap_model:route-aggregate not found in xml schema
<type 'exceptions.ValueError'>
Python 2.7.12: /usr/bin/python
Fri Feb 17 12:32:11 2017

A problem occurred in a Python script. Here is the sequence of
function calls leading up to the error, in the order they occurred.

 /root/contrail-generateDS/generateDS.py in <module>()
 5693 cgitb.enable(format='text')
 5694 logging.basicConfig(level=logging.WARN,)
 5695 main()
 5696
 5697
main = <function main>

 /root/contrail-generateDS/generateDS.py in main()
 5682 #LG LangGenr = CppGenerator()
 5683
 5684 pgenr.parseAndGenerate()
 5685 #LG parseAndGenerate(outFilename, subclassFilename, prefix,
 5686 #LG xschemaFileName, behaviorFilename,
pgenr = <__main__.XsdParserGenerator object>
pgenr.parseAndGenerate = <bound method XsdParserGenerator.parseAndGenerate of <__main__.XsdParserGenerator object>>

 /root/contrail-generateDS/generateDS.py in parseAndGenerate(self=<__main__.XsdParserGenerator object>)
 1137 #debug_show_elements(root)
 1138 infile.seek(0)
 1139 self._Generator.generate(root, infile, self.outFilename)
 1140
 1141 #LG #
self = <__main__.XsdParserGenerator object>
self._Generator = <ccmap.IFMapGenerator object>
self._Generator.generate = <bound method IFMapGenerator.generate of <ccmap.IFMapGenerator object>>
root = <XschemaElement name: "" type: "xsd:string">
infile = <StringIO.StringIO instance>
self.outFilename = '/root/output'

 /root/contrail-generateDS/ccmap.py in generate(self=<ccmap.IFMapGenerator object>, root=<XschemaElement name: "" type: "xsd:string">, infile=<StringIO.StringIO instance>, outFilename='/root/output')
  199 self._GenerateDeviceApi(root)
  200 elif self._genCategory == 'golang-api':
  201 self._GenerateGoLangApi(root)
  202 elif self._genCategory == 'json-schema':
  203 self._GenerateJsonSchema(root)
self = <ccmap.IFMapGenerator object>
self._GenerateGoLangApi = <bound method IFMapGenerator._GenerateGoLangApi of <ccmap.IFMapGenerator object>>
root = <XschemaElement name: "" type: "xsd:string">

 /root/contrail-generateDS/ccmap.py in _GenerateGoLangApi(self=<ccmap.IFMapGenerator object>, xsd_root=<XschemaElement name: "" type: "xsd:string">)
  172 apigen = GoLangApiGenerator(self._Parser, self._cTypesDict,
  173 self._Identifiers, self._Metadata)
  174 apigen.Generate(self._Parser.outFilename)
  175
  176 def _GenerateJsonSchema(self, xsd_root):
apigen = <golang_api.GoLangApiGenerator object>
apigen.Generate = <bound method GoLangApiGenerator.Generate of <golang_api.GoLangApiGenerator object>>
self = <ccmap.IFMapGenerator object>
self._Parser = <__main__.XsdParserGenerator object>
self._Parser.outFilename = '/root/output'

 /root/contrail-generateDS/golang_api.py in Generate(self=<golang_api.GoLangApiGenerator object>, dirname='/root/output')
  822 filename = os.path.join(
  823 dirname, ident.getCIdentifierName() + ".go")
  824 self._GenerateObject(ident, filename)
  825
  826 self._PromoteInnerTypes()
self = <golang_api.GoLangApiGenerator object>
self._GenerateObject = <bound method GoLangApiGenerator._GenerateObject of <golang_api.GoLangApiGenerator object>>
ident = <ifmap_model.IFMapIdentifier object>
filename = u'/root/output/domain.go'

 /root/contrail-generateDS/golang_api.py in _GenerateObject(self=<golang_api.GoLangApiGenerator object>, ident=<ifmap_model.IFMapIdentifier object>, filename=u'/root/output/domain.go')
   70 self._GenerateConstFlags(ident, file)
   71 self._GenerateObjectStruct(ident, file)
   72 self._GenerateGenericMethods(ident, file)
   73 self._GeneratePropertyMethods(ident, file)
   74 self._GenerateChildrenMethods(ident, file)
self = <golang_api.GoLangApiGenerator object>
self._GenerateGenericMethods = <bound method GoLangApiGenerator._GenerateGenericMethods of <golang_api.GoLangApiGenerator object>>
ident = <ifmap_model.IFMapIdentifier object>
file = <open file u'/root/output/domain.go', mode 'w'>

 /root/contrail-generateDS/golang_api.py in _GenerateGenericMethods(self=<golang_api.GoLangApiGenerator object>, ident=<ifmap_model.IFMapIdentifier object>, file=<open file u'/root/output/domain.go', mode 'w'>)
  284 parents = ident.getParents()
  285 if parents:
  286 (parent, meta) = parents[0]
  287 quoted_list = map(lambda x: '"%s"' % x, parent.getDefaultFQName())
  288 parent_fqn = ', '.join(quoted_list)
parent undefined
meta undefined
parents = [(<ifmap_model.IFMapIdentifier object>, <ifmap_model.IFMapLink object>, False)]
<type 'exceptions.ValueError'>: too many values to unpack
    __class__ = <type 'exceptions.ValueError'>
    __delattr__ = <method-wrapper '__delattr__' of exceptions.ValueError object>
    __dict__ = {}
    __doc__ = 'Inappropriate argument value (of correct type).'
    __format__ = <built-in method __format__ of exceptions.ValueError object>
    __getattribute__ = <method-wrapper '__getattribute__' of exceptions.ValueError object>
    __getitem__ = <method-wrapper '__getitem__' of exceptions.ValueError object>
    __getslice__ = <method-wrapper '__getslice__' of exceptions.ValueError object>
    __hash__ = <method-wrapper '__hash__' of exceptions.ValueError object>
    __init__ = <method-wrapper '__init__' of exceptions.ValueError object>
    __new__ = <built-in method __new__ of type object>
    __reduce__ = <built-in method __reduce__ of exceptions.ValueError object>
    __reduce_ex__ = <built-in method __reduce_ex__ of exceptions.ValueError object>
    __repr__ = <method-wrapper '__repr__' of exceptions.ValueError object>
    __setattr__ = <method-wrapper '__setattr__' of exceptions.ValueError object>
    __setstate__ = <built-in method __setstate__ of exceptions.ValueError object>
    __sizeof__ = <built-in method __sizeof__ of exceptions.ValueError object>
    __str__ = <method-wrapper '__str__' of exceptions.ValueError object>
    __subclasshook__ = <built-in method __subclasshook__ of type object>
    __unicode__ = <built-in method __unicode__ of exceptions.ValueError object>
    args = ('too many values to unpack',)
    message = 'too many values to unpack'

The above is a description of an error in a Python program. Here is
the original traceback:

Traceback (most recent call last):
  File "./generateDS.py", line 5695, in <module>
    main()
  File "./generateDS.py", line 5684, in main
    pgenr.parseAndGenerate()
  File "./generateDS.py", line 1139, in parseAndGenerate
    self._Generator.generate(root, infile, self.outFilename)
  File "/root/contrail-generateDS/ccmap.py", line 201, in generate
    self._GenerateGoLangApi(root)
  File "/root/contrail-generateDS/ccmap.py", line 174, in _GenerateGoLangApi
    apigen.Generate(self._Parser.outFilename)
  File "/root/contrail-generateDS/golang_api.py", line 824, in Generate
    self._GenerateObject(ident, filename)
  File "/root/contrail-generateDS/golang_api.py", line 72, in _GenerateObject
    self._GenerateGenericMethods(ident, file)
  File "/root/contrail-generateDS/golang_api.py", line 286, in _GenerateGenericMethods
    (parent, meta) = parents[0]
ValueError: too many values to unpack

Git commits:
contrail-generateDS 08bfd5e685f04ed90229d91b1b48a36a7ecbff16
contrail-controller d8917495817dea4cf05dc478cd6312bd7597e2af