Steps to Reproduce:
* add a statement with [[ https://wikidata.beta.wmflabs.org/w/index.php?title=Property%3AP766 | property P766 ]] and some date
* observe wdqs-updater log on the test system via `docker logs -f wdqs-updater`
Actual Results:
```
15:59:45.519 [main] INFO o.w.q.r.t.change.RecentChangesPoller - Got 1 changes, from Q27@105@20200721155942|115 to Q27@105@20200721155942|115
15:59:45.878 [update 3] WARN org.wikidata.query.rdf.tool.Updater - Contained error syncing. Giving up on Q27
org.wikidata.query.rdf.tool.exception.ContainedException: RDF parsing error for http://wikidata-federated-properties.wmflabs.org/wiki/Special:EntityData/Q27.ttl?flavor=dump&nocache=1595347185568
at org.wikidata.query.rdf.tool.wikibase.WikibaseRepository.collectStatementsFromUrl(WikibaseRepository.java:417)
at org.wikidata.query.rdf.tool.wikibase.WikibaseRepository.fetchRdfForEntity(WikibaseRepository.java:473)
at org.wikidata.query.rdf.tool.wikibase.WikibaseRepository.fetchRdfForEntity(WikibaseRepository.java:449)
at org.wikidata.query.rdf.tool.Updater.handleChange(Updater.java:401)
at org.wikidata.query.rdf.tool.Updater.lambda$fetchDataFromWikibaseAndMunge$7(Updater.java:283)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: org.openrdf.rio.RDFParseException: Namespace prefix 'v' used but not defined [line 78]
at org.openrdf.rio.helpers.RDFParserHelper.reportFatalError(RDFParserHelper.java:440)
at org.openrdf.rio.helpers.RDFParserBase.reportFatalError(RDFParserBase.java:685)
at org.openrdf.rio.turtle.TurtleParser.reportFatalError(TurtleParser.java:1405)
at org.openrdf.rio.helpers.RDFParserBase.getNamespace(RDFParserBase.java:342)
at org.openrdf.rio.turtle.TurtleParser.parseQNameOrBoolean(TurtleParser.java:1065)
at org.openrdf.rio.turtle.TurtleParser.parseValue(TurtleParser.java:643)
at org.openrdf.rio.turtle.TurtleParser.parseObject(TurtleParser.java:527)
at org.openrdf.rio.turtle.TurtleParser.parseObjectList(TurtleParser.java:453)
at org.openrdf.rio.turtle.TurtleParser.parsePredicateObjectList(TurtleParser.java:446)
at org.openrdf.rio.turtle.TurtleParser.parseTriples(TurtleParser.java:409)
at org.openrdf.rio.turtle.TurtleParser.parseStatement(TurtleParser.java:259)
at org.openrdf.rio.turtle.TurtleParser.parse(TurtleParser.java:214)
at org.wikidata.query.rdf.tool.wikibase.WikibaseRepository.collectStatementsFromUrl(WikibaseRepository.java:408)
... 8 common frames omitted
```
Expected Results:
* wdqs-updater should not throw an error when updating an item with that property
* item should be returned by [[ https://query-federated-properties.wmflabs.org/#PREFIX%20fpwdt%3A%20%3Chttp%3A%2F%2Fwikidata.beta.wmflabs.org%2Fprop%2Fdirect%2F%3E%0ASELECT%20%3Fitem%20%3FitemLabel%20%3FpubDate%20%0AWHERE%20%7B%20%3Fitem%20fpwdt%3AP766%20%3FpubDate%20.%20%7D%0A | this SPARQL query on https://query-federated-properties.wmflabs.org/ ]]:
```
PREFIX fpwdt: <http://wikidata.beta.wmflabs.org/prop/direct/>
SELECT ?item ?itemLabel ?pubDate
WHERE { ?item fpwdt:P766 ?pubDate . }
```