(ITS#7736) back-mdb corrupts during write operations

Full_Name: Quanah Gibson-Mount Version: 2.4.37 OS: Linux 2.6 URL: ftp://ftp.openldap.org/incoming/ Submission from: (NULL) (75.111.58.125) Found after upgrading to OpenLDAP 2.4.37 + the last two commits to liblmdb: 527168fe mdb_search_candidates: id=1 first=77 last=77 slapd: ./../../../libraries/liblmdb/mdb.c:4596: mdb_page_get: Assertion `p != ((void *)0)' failed. Aborted slapd last logged: Oct 30 15:50:14 zqa-061 slapd[25442]: slap_queue_csn: queing 0x7f761e2091a0 20131030155014.945701Z#000000#000#000000 Oct 30 15:50:14 zqa-061 slapd[25442]: slap_graduate_commit_csn: removing 0x4cb8b70 20131030155014.945701Z#000000#000#000000