LuceneOptimizedStoredFieldsFormatTest > testNumericField cannot find stored fields sometimes

[ScottDugas]

This happens sometimes (with the same seed):

LuceneOptimizedStoredFieldsFormatTest > testNumericField FAILED
    com.apple.foundationdb.record.RecordCoreStorageException: Could not find stored fields
        at __randomizedtesting.SeedInfo.seed([C185081D42F0F43C:91AB1306856D114E]:0)
        at app//com.apple.foundationdb.record.lucene.directory.FDBDirectory.readStoredFields(FDBDirectory.java:539)
        at app//com.apple.foundationdb.record.lucene.codec.LuceneOptimizedStoredFieldsReader.visitDocument(LuceneOptimizedStoredFieldsReader.java:76)
        at app//org.apache.lucene.index.CodecReader.document(CodecReader.java:84)
        at app//org.apache.lucene.index.IndexReader.document(IndexReader.java:352)
        at app//org.apache.lucene.index.BaseStoredFieldsFormatTestCase.testNumericField(BaseStoredFieldsFormatTestCase.java:297)
        at app//com.apple.foundationdb.record.lucene.codec.LuceneOptimizedStoredFieldsFormatTest.testNumericField(LuceneOptimizedStoredFieldsFormatTest.java:88)