Test cases for (acl, masks) pairs that cannot be represented as
pure ACLs

$ rm -rf d
$ mkdir d
$ cd d

$ touch x

$ nfs4acl --set 'group@:rw::allow' x
$ chmod 600 x
$ ls -l x | cut -d ' ' -f 1
> -rw-------
$ nfs4acl --get x
> x:
>
$ rm -f x

$ cd ..
$ rm -rf d
