rollup merge of #23908: aturon/stab-more-stragglers

* The `io::Seek` trait.
* The `Iterator::{partition, unsip}` methods.
* The `Vec::into_boxed_slice` method.
* The `LinkedList::append` method.
* The `{or_insert, or_insert_with` methods in the `Entry` APIs.

r? @alexcrichton

1 files changed, 1 insertions, 1 deletions

diff --git a/src/libcollections/vec.rs b/src/libcollections/vec.rs
index 2ac50c6cabf..39601783e42 100644
--- a/src/libcollections/vec.rs
+++ b/src/libcollections/vec.rs
@@ -389,7 +389,7 @@ impl<T> Vec<T> {
     /// Note that this will drop any excess capacity. Calling this and
     /// converting back to a vector with `into_vec()` is equivalent to calling
     /// `shrink_to_fit()`.
-    #[unstable(feature = "collections")]
+    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn into_boxed_slice(mut self) -> Box<[T]> {
         self.shrink_to_fit();
         unsafe {