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

     {