warnings during installation (in chinese)

I got these warnings during installation. I'm using simplified chinese. I'm using Firefox and Ubuntu.

Notice: Undefined property: stdClass::$ostype in /home/andrew/Desktop/code/moodle/int/master/lib/filelib.php on line 2962
Call Stack

1. Time Memory Function Location
   1 0.0019 393624
   Unknown macro: {main}

   ( ) ../install.php:0
   2 0.1902 15330192 lang_installer->run( ) ../install.php:363
   3 0.1903 15330704 lang_installer->install_language_pack( ) ../componentlib.class.php:640
   4 0.1904 15332424 component_installer->install( ) ../componentlib.class.php:779
   5 0.1904 15333056 component_installer->need_upgrade( ) ../componentlib.class.php:277
   6 0.1904 15333352 component_installer->get_component_md5( ) ../componentlib.class.php:369
   7 0.1904 15333520 component_installer->get_all_components_md5( ) ../componentlib.class.php:437
   8 0.1904 15334176 download_file_content( ) ../componentlib.class.php:486
   9 0.1906 15337944 curl::get_cacert( ) ../filelib.php:1212

   ( ! ) Notice: Undefined property: stdClass::$ostype in /home/andrew/Desktop/code/moodle/int/master/lib/filelib.php on line 2962
   Call Stack

   1. Time Memory Function Location
      1 0.0019 393624

   ( ) ../install.php:0
   2 0.1902 15330192 lang_installer->run( ) ../install.php:363
   3 0.1903 15330704 lang_installer->install_language_pack( ) ../componentlib.class.php:640
   4 0.1904 15332424 component_installer->install( ) ../componentlib.class.php:779
   5 1.5886 15436192 download_file_content( ) ../componentlib.class.php:292
   6 1.5887 15438456 curl::get_cacert( ) ../filelib.php:1212