Yep, both ```Some(&**tail)``` and ```Some(&'a **tail)``` without success (same compilation error):
```
/Users/bruno.d/Work/rust/src/libcollections/list.rs:55:38: 55:45 error: cannot root managed value long enough
/Users/bruno.d/Work/rust/src/libcollections/list.rs:55                     self.next = Some(&**tail);
```