Better fix for LazyListIterable problem

Better fix for LazyListIterable problem as suggested by Nguyen

Author: odersky

library/src/scala/collection/immutable/LazyListIterable.scala

@@ -311,7 +311,7 @@ final class LazyListIterable[+A] private (lazyState: LazyListIterable.EmptyMarke
         throw new RuntimeException(
           "LazyListIterable evaluation depends on its own result (self-reference); see docs for more info")
 
-      val fun = _tail.asInstanceOf[() ->{this} LazyListIterable[A]^]
+      val fun = _tail.asInstanceOf[() ->{this} LazyListIterable[A]^{this}]
       _tail = MidEvaluation
       val l =
         // `fun` returns a LazyListIterable that represents the state (head/tail) of `this`. We call `l.evaluated` to ensure
@@ -321,7 +321,7 @@ final class LazyListIterable[+A] private (lazyState: LazyListIterable.EmptyMarke
         try fun().evaluated
         // restore `fun` in finally so we can try again later if an exception was thrown (similar to lazy val)
         finally _tail = fun
-      _tail = caps.unsafe.unsafeAssumePure(l.rawTail)
+      _tail = l.rawTail
       _head = l.rawHead
     }
   }