Travis panic

[dpc]

https://travis-ci.org/dpc/mioco/jobs/148753236

failures:

---- tests::simple_mutex_supports_inside_and_outside stdout ----

    thread 'tests::simple_mutex_supports_inside_and_outside' panicked at 'assertion failed: `(left == right)` (left: `7`, right: `9`)', tests.rs:986

stack backtrace:

   1:     0x2b72145751df - std::sys::backtrace::tracing::imp::write::h29f5fdb9fc0a7395

   2:     0x2b721457955b - std::panicking::default_hook::_{{closure}}::h2cc84f0378700526

   3:     0x2b72145786ac - std::panicking::default_hook::hbbe7fa36a995aca0

   4:     0x2b7214578d4e - std::panicking::rust_panic_with_hook::h105c3d42fcd2fb5e

   5:     0x2b7214578bb1 - std::panicking::begin_panic::hbf62ea4a5ff3f9de

   6:     0x2b7214578ada - std::panicking::begin_panic_fmt::h20f5943904e5791d

   7:     0x2b72144f2f1f - mioco::tests::simple_mutex_supports_inside_and_outside::hf64443600be62fc3

   8:     0x2b721453ef26 - _<F as alloc..boxed..FnBox<A>>::call_box::h6c46b1f51a5f97cd

   9:     0x2b72145348f7 - std::panicking::try::call::h8d6a00e6c0ac8b9e

  10:     0x2b72145810e6 - __rust_maybe_catch_panic

  11:     0x2b721453e83e - _<F as alloc..boxed..FnBox<A>>::call_box::h173484225f9723d2

  12:     0x2b7214577154 - std::sys::thread::Thread::new::thread_start::h8f3bd45211e9f5ea

  13:     0x2b7214c7fe99 - start_thread

  14:     0x2b721519e36c - <unknown>

failures: