git add --intent-to-add silently creates empty commits

Hello,

I think this is an unintended behavior, but I might be wrong:

Using `git add -N` allows creating of empty commits:

git init test && cd test echo text > file git add --intent-to-add file git commit -m 'Empty commit' echo $? # prints 0 git log -1 -p --format='' HEAD | wc -l # prints 0 git status -s # prints `AM file`

I'd expect `git commit` to error out instead of producing an empty commit.

I've seen this with git 2.8.1 and 2.10.0.129.g35f6318

Thanks, Aviv