stackoverflow有很好的解决方法，地址如下：
http://stackoverflow.com/questions/8820668/the-current-branch-is-not-configured-for-pull-no-value-for-key-branch-master-mer
用的是只有被投4票的一个答案，完美的解决了我的问题：
To fix this problem in Eclipse, open the Windows menu and select Show View / Other / Git Repositories.
From the Git Repositories tab:
expand your local repository
right click on Remote
click on Create Remote...
Remote name = origin
next to IRI press the Change button
CTRL+SPACE on URI
select the remote location
press Finish
press Save and Push
Again, from the Git Repositories tab:
right click on origin
select Configure Fetch...
on Ref mapping press the Edit (Advanced)...
press Add All Branches Spec
select the Force Update checkbox
press Finish
Again, from the Git Repositories tab:
right click on your local repository
select Properties
press New Entry...
enter the following two keys:
(1)
Key = branch.master.remote
Value = origin
(2)
Key = branch.master.merge
Value = refs/heads/master