Code review comment for lp:~raof/mir/no-ipc-on-compositor-threads

Now a failure in NestedServer.display_orientation_changes_are_forwarded_to_host

...
12:28:26 terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<std::logic_error> >'
12:28:26 what(): stop_server() failed to stop server
12:28:26 ==18875==
12:28:26 ==18875== Process terminating with default action of signal 6 (SIGABRT)
12:28:26 ==18875== at 0x458AEA9: raise (raise.c:54)
12:28:26 ==18875== by 0x458C406: abort (abort.c:89)
12:28:26 ==18875== by 0x4420D34: __gnu_cxx::__verbose_terminate_handler() (in /usr/lib/i386-linux-gnu/libstdc++.so.6.0.21)
12:28:26 ==18875== by 0x441E832: ??? (in /usr/lib/i386-linux-gnu/libstdc++.so.6.0.21)
12:28:26 ==18875== by 0x441D648: ??? (in /usr/lib/i386-linux-gnu/libstdc++.so.6.0.21)
12:28:26 ==18875== by 0x441DE10: __gxx_personality_v0 (in /usr/lib/i386-linux-gnu/libstdc++.so.6.0.21)
12:28:26 ==18875== by 0x453A3DE: ??? (in /lib/i386-linux-gnu/libgcc_s.so.1)
12:28:26 ==18875== by 0x453A856: _Unwind_Resume (in /lib/i386-linux-gnu/libgcc_s.so.1)
12:28:26 ==18875== by 0x8727D93: ~unique_lock (mutex:450)
12:28:26 ==18875== by 0x8727D93: mir_test_framework::AsyncServerRunner::wait_for_server_exit() (async_server_runner.cpp:117)
...

I think that's (at least) a failure too many to be a coincidence.

Is this MP introducing a shutdown race that can deadlock?