We noticed on the demo server, that dspace database migrate does not create the initial groups (Administrator, Anonymous). This only occurs if RDF (dspace-rdf) is enabled.
Debugging showed that the RDFConsumer#end() creates an own ReadOnly Context and aborts it at the end. This aborts the whole connection and drops the inserted groups.
The cause is, abort on a read only context, aborts the connection, too. This was introduced by the removal of a check for read only here: https://github.com/DSpace/DSpace/commit/1ccd6d1e13563357849d8dd6ac60d6320d71e4c7?diff=split#diff-cbd2f003ca152958b516d0e949719ef3L521