DICOMWeb plugin - QIDO-RS studies instances returns nothing when study has more than one series

Hello,

QIDO-RS supports querying for all instances in a study like this:

/studies/{studyInstanceUid}/instances

which maps to SearchForInstances here:

https://bitbucket.org/sjodogne/orthanc-dicomweb/src/da70170d367e7c04d4aa36e7f46859c76f96bdfa/Plugin/QidoRs.cpp?at=default#QidoRs.cpp-858

Which is returning an empty result if there are more than one series in the study.

Chris