ここで何が間違っていますか?
$ git submodule foreach git pull # fails
$ cd Submodules/MBProgressHUD/
$ git diff
$ git checkout master
$ git pull
$ cd ..
$ cd ..
$ git submodule foreach git pull # fails
$ cd Submodules/ShareKit/
$ ls
$ git pull master
$ git checkout master
$ git diff
$ git submodule foreach git pull # fails
$ git status
$ git fetch
$ git pull
$ git submodule foreach git pull # fails
最後のものを示しますが、基本的にはすべて次のようになります。
Entering 'Submodules/JSONKit'
You are not currently on a branch. Please specify which
branch you want to merge with. See git-pull(1) for details.
git pull <remote> <branch>
Stopping at 'Submodules/JSONKit'; script returned non-zero status.