diff.noprefix breaks rebase

Hi,

It seems that diff.noprefix causes rebase to misplace files that exist
in paths that have names similiar to the git diff default prefixes. So a
commit that adds /db/somefile will after a rebase place the file
into /somefile. 

Example test-case below:

mkdir test
cd test
git init
touch x
git add x
git commit -m x
touch z
git add z
git commit -m z
mkdir db
touch db/y
git add db
git commit -m db
git config diff.noprefix true
git rebase --onto master^^ master^ master
ls -R
.:
x  y

expecting to see:
ls -R
.:
db  x

./db:
y


Regards,
Tarmo