mac git pull or pull down the code is too slow, may be the reason

solve

 

sudo vi /private/etc/hosts

Open after entering the editor, the last line of the movable press "on the keyboard o" key, the input state will jump to the next line. So that you can start editing the hosts file a

 

Editing the hosts file, press the keyboard "the Esc " button, enter ": WQ " will be saved automatically, you can end editor

151.101.76.249 github.global.ssl.fastly.net

192.30.253.112 github.com