When tcbdbopen fails to open a database file wrong pointer is returned
instead of NULL pointer.

Patch by Edgar Hoch

RHBZ#1004110

--- ypserv-2.31/lib/yp_db.c.orig	2013-04-10 16:42:21.000000000 +0200
+++ ypserv-2.31/lib/yp_db.c	2013-09-04 02:38:04.515428554 +0200
@@ -181,6 +181,12 @@ 
       	}
       else if (debug_flag)
 	log_msg ("\t\t->Returning OK!");
+      if ( !isok )
+	{
+	  /* DB not successful opened. Close database object and set return value to NULL. */
+	  tcbdbdel (dbp);
+	  dbp = NULL;
+	}
     }
   else
     {