Bug #12793170 MYSQLTEST: PROVIDE ACCESS TO ERROR NAMES THROUGH NUMERIC

CODES AND VICE VERSA
  Followup: Some statement may give errors not in the list,
  map these to "<Unknown>" rather than failing.

client/mysqltest.cc

@@ -4732,10 +4732,10 @@ const char *get_errname_from_code (uint error_code)
        DBUG_RETURN(e->name);
      }
    }
-   die("Unknown SQL error code '%d'", error_code);
+   /* Apparently, errors without known names may occur */
+   DBUG_RETURN("<Unknown>");
 } 
 
-
 void do_get_errcodes(struct st_command *command)
 {
   struct st_match_err *to= saved_expected_errors.err;