Fallout of c933d44f7b

src/libstd/sys/unix/backtrace.rs

@@ -118,7 +118,7 @@ fn backtrace(buf: *mut *mut libc::c_void,
     // local, it still displays much nicer backtraces when a
     // couple of tasks panic simultaneously
     static LOCK: StaticMutex = MUTEX_INIT;
-    let _g = unsafe { LOCK.lock() };
+    let _g = LOCK.lock();
 
     try!(writeln!(w, "stack backtrace:"));
     // 100 lines should be enough