git bug?

hello,

Using .git/info/exclude file to ignore some of my directories, I notice a curious think I took for a bug :

I wanted to exclude all except that is inside my /TED/ directory
I wrote a file exclude first as this


*
!/TED/


but this doesn't work and is dangerous because no warning, and git status said (after I realize commit and push on server)
working copy is clear.
fortunately looking at repository I realize the mistake and trying a "git add" tells me there is something wrong in the
exclude file
I changed it as this

/*
!/TED/

and it works
but I don't know exactly why 
Have you a begin of answer ?

thanks a lot in advance for any answer