Ticket 47889 - DS crashed during ipa-server-install on test_ava_filter

Bug Description:
	During a MOD the target entry is duplicated and mods are applied
	on the duplicated entry that is set in the pblock (SLAPI_MODIFY_EXISTING_ENTRY).
	In case of transient DB error, ldbm_back_modify retries.
	But when retrying the duplicated entry will be freed and needs to be duplicated again.
	The new duplicated entry needs to be set in the pblock.
	https://fedorahosted.org/389/ticket/47834 erronously skip the setting of SLAPI_MODIFY_EXISTING_ENTRY

Fix Description:
	Set SLAPI_MODIFY_EXISTING_ENTRY during mod/retry

https://fedorahosted.org/389/ticket/47889

Reviewed by: ?

Platforms tested: F20

Flag Day: no

Doc impact: no

ldap/servers/slapd/back-ldbm/ldbm_modify.c

@@ -529,6 +529,7 @@ ldbm_back_modify( Slapi_PBlock *pb )
 					CACHE_REMOVE(&inst->inst_cache, ec);
 				}
 				CACHE_RETURN(&inst->inst_cache, &ec);
+				slapi_pblock_set( pb, SLAPI_MODIFY_EXISTING_ENTRY, original_entry->ep_entry );
 				ec = original_entry;
 				original_entry = tmpentry;
 				tmpentry = NULL;