use the slice_pat hack in libstd too

src/libstd/lib.rs

@@ -467,3 +467,15 @@ pub mod __rand {
 // the rustdoc documentation for primitive types. Using `include!`
 // because rustdoc only looks for these modules at the crate level.
 include!("primitive_docs.rs");
+
+// FIXME(stage0): remove this after a snapshot
+// HACK: this is needed because the interpretation of slice
+// patterns changed between stage0 and now.
+#[cfg(stage0)]
+fn slice_pat<'a, 'b, T>(t: &'a &'b [T]) -> &'a &'b [T] {
+    t
+}
+#[cfg(not(stage0))]
+fn slice_pat<'a, 'b, T>(t: &'a &'b [T]) -> &'b [T] {
+    *t
+}