Steps to Reproduce:
Use a repo to a site and find an Item with referenced claims. The first time you index a claim and run .getSources() it will produce a claim of its own. After that it will only ever produce an empty list, even if you run it on a difference referenced claim on the same Item. You can run it once per Item but after it only ever returns an empty list.
Actual Results:
[OrderedDict([('P28', [Claim.fromJSON(DataSite("komorido", "komorido"), {'snaktype': 'value', 'property': 'P28', 'datatype': 'wikibase-item', 'datavalue': {'value': {'entity-type': 'item', 'numeric-id': 21}, 'type': 'wikibase-entityid'}, 'hash': '1eff422c8858dd02c904b0fae03e042baffee67e'})])])]
[]
Expected Results:
[OrderedDict([('P28', [Claim.fromJSON(DataSite("komorido", "komorido"), {'snaktype': 'value', 'property': 'P28', 'datatype': 'wikibase-item', 'datavalue': {'value': {'entity-type': 'item', 'numeric-id': 21}, 'type': 'wikibase-entityid'}, 'hash': '1eff422c8858dd02c904b0fae03e042baffee67e'})])])]
[OrderedDict([('P28', [Claim.fromJSON(DataSite("komorido", "komorido"), {'snaktype': 'value', 'property': 'P28', 'datatype': 'wikibase-item', 'datavalue': {'value': {'entity-type': 'item', 'numeric-id': 21}, 'type': 'wikibase-entityid'}, 'hash': '1eff422c8858dd02c904b0fae03e042baffee67e'})])])]