Address sporadic test failure in UNICEF / provisionagreement

[khaeru]

Daily test runs of TestUNICEF.test_endpoint[provisionagreement] sometimes (not always) fail with messages like this one:

E           RuntimeError: 1 uncollected items

sdmx/reader/xml.py:277: RuntimeError
----------------------------- Captured stdout call -----------------------------

--- <class 'sdmx.message.StructureMessage'> ---
{2: <sdmx.StructureMessage>
  <Header>
    id: 'IREF683155'
    prepared: '2021-08-25T05:11:51+00:00'
    receiver: <Agency not_supplied>
    sender: <Agency UNICEF>
    source: 
    test: False
  DataflowDefinition (49): CHILD_RELATED_SDG PT_FGM CHLD_PVTY CME_COUNT...
  DataProviderScheme (1): DATA_PROVIDERS
  ProvisionAgreement (49): CHILD_RELATED_SDG_UNICEF_UNICEF CHLD_PROT_FG...}

--- <class 'sdmx.model.Agency'> ---
{'UNICEF': <Agency UNICEF>}

--- _stash ---
{252: {'Name': {250: ('en', 'UNICEF for Work Transition')}, 'Description': {}}}

------------------------------ Captured log call -------------------------------
INFO     sdmx.client:client.py:445 Request https://sdmx.data.unicef.org/ws/public/sdmxapi/rest/provisionagreement/UNICEF/latest

The response at that URL gives a message including the following (chosen based on the uncollected items):

<mes:Structure>
  <mes:Structures>
    <str:ProvisionAgreements>
      …
      <str:ProvisionAgreement urn="urn:sdmx:org.sdmx.infomodel.registry.ProvisionAgreement=UNICEF:WT_UNICEF_UNICEF(1.0)" isExternalReference="false" agencyID="UNICEF" id="WT_UNICEF_UNICEF" isFinal="false" version="1.0">
        <com:Name xml:lang="en">UNICEF for Work Transition</com:Name>
        <str:StructureUsage>
          <Ref package="datastructure" agencyID="UNICEF" id="WT" version="1.0" class="Dataflow"/>
        </str:StructureUsage>
        <str:DataProvider>
          <Ref maintainableParentID="DATA_PROVIDERS" package="base" maintainableParentVersion="1.0" agencyID="UNICEF" id="UNICEF" class="DataProvider"/>
        </str:DataProvider>
      </str:ProvisionAgreement>
    </str:ProvisionAgreements>
  </mes:Structures>
</mes:Structure>

• Investigate the parse failure.
• Fix, adding tests.