Fix VCS error when fetching some rows

Error observed in 5.4.1 during selenium tests:
Exception: java.lang.IllegalStateException. message: ABSENT
at org.nuxeo.ecm.core.storage.sql.PersistenceContext.getFragmentFromFetchedRow(PersistenceContext.java:591)
at org.nuxeo.ecm.core.storage.sql.PersistenceContext.getFragmentsFromFetchedRows(PersistenceContext.java:548)
at org.nuxeo.ecm.core.storage.sql.PersistenceContext.getFromMapper(PersistenceContext.java:478)
at org.nuxeo.ecm.core.storage.sql.PersistenceContext.getMulti(PersistenceContext.java:520)
at org.nuxeo.ecm.core.storage.sql.SessionImpl.getNodesByIds(SessionImpl.java:626)
at org.nuxeo.ecm.core.storage.sql.ra.ConnectionImpl.getNodesByIds(ConnectionImpl.java:190)
at org.nuxeo.ecm.core.storage.sql.coremodel.SQLSession.getDocumentsById(SQLSession.java:624)
at org.nuxeo.ecm.core.storage.sql.coremodel.SQLQueryResult.getDocumentModels(SQLQueryResult.java:102)
at org.nuxeo.ecm.core.api.AbstractSession.query(AbstractSession.java:1484)
... 92 more