The patch below fixes the crash, however I'd appreciate a review before committing in case I misunderstood why that code might be needed.
The first periodic expiry runs immediately after startup completes, and AFAICT does everything this one would have; so the window for returning stale data should be short. Thanks. ftp://ftp.openldap.org/incoming/20150519_rtandy_ITS-8133-avoid-mods-during-dds_db_open.patch
