Merge ref 'a015919e54c6' from rust-lang/rust

Pull recent changes from https://github.com/rust-lang/rust via Josh.

Upstream ref: a015919e54c60b1b2bec7a98dec478cfc4a48f4e
Filtered ref: 1867c58
Upstream diff: rust-lang/rust@4ba1cf9...a015919

This merge was created using https://github.com/rust-lang/josh-sync.

Author: The Miri Cronjob Bot

tests/pass/btreemap.rs

@@ -1,7 +1,6 @@
 //@revisions: stack tree
 //@[tree]compile-flags: -Zmiri-tree-borrows
 //@compile-flags: -Zmiri-strict-provenance
-#![feature(btree_extract_if)]
 use std::collections::{BTreeMap, BTreeSet};
 use std::mem;