stack trace 2

thread 'main' panicked at 'invalid key', /home/maidsafe/.cargo/registry/src/github.com-1ecc6299db9ec823/slab-0.4.2/src/lib.rs:798:18
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:39
   1: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:70
   2: std::panicking::default_hook::{{closure}}
             at src/libstd/sys_common/backtrace.rs:58
             at src/libstd/panicking.rs:200
   3: std::panicking::default_hook
             at src/libstd/panicking.rs:215
   4: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:478
   5: std::panicking::begin_panic
   6: quinn_proto::endpoint::Endpoint::timeout
   7: <quinn::Driver as futures::future::Future>::poll
   8: <futures::future::map_err::MapErr<A, F> as futures::future::Future>::poll
   9: futures::task_impl::std::set
  10: tokio_current_thread::CurrentRunner::set_spawn
  11: <tokio_current_thread::scheduler::Scheduler<U>>::tick
  12: <tokio_current_thread::Entered<'a, P>>::block_on
  13: <std::thread::local::LocalKey<T>>::with
  14: <std::thread::local::LocalKey<T>>::with
  15: <std::thread::local::LocalKey<T>>::with
  16: <std::thread::local::LocalKey<T>>::with
  17: tokio::runtime::current_thread::runtime::Runtime::block_on
  18: quinn_tests::main
  19: std::rt::lang_start::{{closure}}
  20: std::panicking::try::do_call
             at src/libstd/rt.rs:49
             at src/libstd/panicking.rs:297
  21: __rust_maybe_catch_panic
             at src/libpanic_unwind/lib.rs:92
  22: std::rt::lang_start_internal
             at src/libstd/panicking.rs:276
             at src/libstd/panic.rs:388
             at src/libstd/rt.rs:48
  23: main
  24: __libc_start_main
  25: _start