Auto merge of #955 - RalfJung:rustup, r=RalfJung

remove libstd backtrace work-around

Author: bors

rust-version

@@ -1 +1 @@
-96d07e0ac9f0c56b95a2561c6cedac0b23a5d2a3
+a44881d892fb4f4a8ed93f8f392bab942fac7a41

src/bin/cargo-miri.rs

@@ -288,9 +288,7 @@ fn setup(ask_user: bool) {
 default_features = false
 # We need the `panic_unwind` feature because we use the `unwind` panic strategy.
 # Using `abort` works for libstd, but then libtest will not compile.
-# FIXME: Temporarily enabling backtrace feature to work around
-# <https://github.com/rust-lang/rust/issues/64410>.
-features = ["panic_unwind", "backtrace"]
+features = ["panic_unwind"]
 
 [dependencies.test]
         "#).unwrap();