This query gives an error, where no writing should occur:

```
PREFIX rdfs:   <http://www.w3.org/2000/01/rdf-schema#>
PREFIX rdf:    <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX dcat:   <http://www.w3.org/ns/dcat#>
PREFIX dct:    <http://purl.org/dc/terms/>
PREFIX dcv: <https://dataid.dbpedia.org/databus-cv#>
PREFIX databus: <https://dataid.dbpedia.org/databus#>
SELECT DISTINCT * WHERE
{
    SERVICE <https://databus.dbpedia.org/sparql>
    {
        ?distribution databus:file ?file .
        {
            SELECT ?version { 
                ?ds databus:group <https://databus.dbpedia.org/dbpedia/mappings> . 
                ?ds dct:hasVersion ?version . 
            } 
        }
    }
}
```

Error:
`Virtuoso RDF02 Error SR619: SPARUL LOAD SERVICE DATA access denied: database user 107 (SPARQL) has no write permission on graph https://databus.dbpedia.org/sparql`

However, omitting the `?distribution databus:file ?file .` in the above query makes it work.
I am using the docker image `pkleef/virtuoso-opensource-7:latest` which includes the fix for https://github.com/openlink/virtuoso-opensource/issues/571
Federated SELECT with nesting leads to write permission error
This is a GitHub Issue
repo:virtuoso-opensource
owner:openlink
Title : Federated SELECT with nesting leads to write permission error
Issue date:

--- start body ---
This query gives an error, where no writing should occur:

```
PREFIX rdfs:   <http://www.w3.org/2000/01/rdf-schema#>
PREFIX rdf:    <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX dcat:   <http://www.w3.org/ns/dcat#>
PREFIX dct:    <http://purl.org/dc/terms/>
PREFIX dcv: <https://dataid.dbpedia.org/databus-cv#>
PREFIX databus: <https://dataid.dbpedia.org/databus#>
SELECT DISTINCT * WHERE
{
    SERVICE <https://databus.dbpedia.org/sparql>
    {
        ?distribution databus:file ?file .
        {
            SELECT ?version { 
                ?ds databus:group <https://databus.dbpedia.org/dbpedia/mappings> . 
                ?ds dct:hasVersion ?version . 
            } 
        }
    }
}
```

Error:
`Virtuoso RDF02 Error SR619: SPARUL LOAD SERVICE DATA access denied: database user 107 (SPARQL) has no write permission on graph https://databus.dbpedia.org/sparql`

However, omitting the `?distribution databus:file ?file .` in the above query makes it work.
I am using the docker image `pkleef/virtuoso-opensource-7:latest` which includes the fix for https://github.com/openlink/virtuoso-opensource/issues/571
--- end body ---
