git pull 时可能出现这样的错误：

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@  
@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @  
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@  
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!  
Someone could be eavesdropping on you right now (man-in-the-middle attack)!  
It is also possible that a host key has just been changed.  
The fingerprint for the RSA key sent by the remote host is  
07:36:8e:d0:72:88:38:f7:21:10:c3:12:d6:35:ad:55.  
Please contact your system administrator.  
Add correct host key in /Users/watsy/.ssh/known_hosts to get rid of this message.  
Offending RSA key in /Users/watsy/.ssh/known_hosts:1  
RSA host key for 192.168.2.108 has changed and you have requested strict checking.  
Host key verification Failed.  

解决办法：

rm -rf ~/.ssh/known_hosts  

从新ssh连接，ok了。