fails:Net::FTP.open when passed no block returns a new Net::FTP instance
fails:Net::FTP.open when passed no block passes the passed arguments down to Net::FTP.new
fails:Net::FTP.open when passed a block yields a new Net::FTP instance to the passed block
fails:Net::FTP.open when passed a block closes the Net::FTP instance after yielding
fails:Net::FTP.open when passed a block closes the Net::FTP instance even if an exception is raised while yielding
fails:Net::FTP.open when passed a block returns the block's return value
