blockchain_market_list_covers command broken: default base_symbol should be BTS but not XTS

[abitmore]

>> blockchain_market_list_covers USD

10 assert_exception: Assert Exception
arec.valid(): 
    {}
    bitshares  chain_database.cpp:2093 bts::blockchain::chain_database::get_asset_id

    {"symbol":"XTS"}
    bitshares  chain_database.cpp:2095 bts::blockchain::chain_database::get_asset_id

    {"quote_symbol":"USD","limit":4294967295}
    bitshares  chain_database.cpp:2884 bts::blockchain::chain_database::get_market_covers

    {}
    bitshares  common_api_client.cpp:2208 bts::rpc_stubs::common_api_client::blockchain_market_list_covers

    {"command":"blockchain_market_list_covers"}
    bitshares  cli.cpp:626 bts::cli::detail::cli_impl::execute_command

>> help blockchain_market_list_covers

Usage:
blockchain_market_list_covers <quote_symbol> [base_symbol] [limit]                                    Returns the covers side of the order book for a given market
Returns the covers side of the order book for a given market

Parameters:
  quote_symbol (asset_symbol, required): the symbol name the market is quoted in
  base_symbol (asset_symbol, optional, defaults to "XTS"): the symbol name the market is collateralized in
  limit (uint32_t, optional, defaults to "-1"): the maximum number of items to return, -1 for all

Returns:
  market_order_array

aliases: market_covers

[vikramrajkumar]

base_symbol should in fact be removed since only BTS can be used as collateral.