TimerLoop crashes on SIGINT

[sgkim126]

stack backtrace:
   0:     0x5620918d8876 - backtrace::backtrace::libunwind::trace::h89ce6f97ed704bb8
                        at /home/sgkim126/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.7/src/backtrace/libunwind.rs:53
                         - backtrace::backtrace::trace::h2ea11176de8b52b9
                        at /home/sgkim126/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.7/src/backtrace/mod.rs:42
   1:     0x5620918d2d13 - backtrace::capture::Backtrace::new_unresolved::h12c4aafe92d9af95
                        at /home/sgkim126/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.7/src/capture.rs:88
   2:     0x5620918d2c6d - backtrace::capture::Backtrace::new::hc701411efe5ca320
                        at /home/sgkim126/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.7/src/capture.rs:63
   3:     0x5620906d13c3 - panic_hook::panic_hook::hbb6739b4e365caf1
                        at util/panic_hook/src/lib.rs:53
   4:     0x5620906d19e7 - core::ops::function::Fn::call::h2dc66d0d14de4fcb
                        at /rustc/6c2484dc3c532c052f159264e970278d8b77cdc9/src/libcore/ops/function.rs:69
   5:     0x5620922c1ce8 - rust_panic_with_hook
                        at src/libstd/panicking.rs:482
   6:     0x5620922c1781 - continue_panic_fmt
                        at src/libstd/panicking.rs:385
   7:     0x5620922c1665 - rust_begin_unwind
   8:     0x5620922df57c - panic_fmt
                        at src/libcore/panicking.rs:85
   9:     0x562090add354 - core::result::unwrap_failed::h2817faf90ff1a575
                        at /rustc/6c2484dc3c532c052f159264e970278d8b77cdc9/src/libcore/macros.rs:17
  10:     0x562090abe15a - <core::result::Result<T, E>>::expect::h64de81945013c413
                        at /rustc/6c2484dc3c532c052f159264e970278d8b77cdc9/src/libcore/result.rs:825
  11:     0x562090a282bd - <codechain_core::client::client::Client as codechain_core::client::ResealTimer>::set_min_timer::h0eb20439134cfd92
                        at core/src/client/client.rs:363
  12:     0x562090a5f291 - <codechain_core::miner::miner::Miner as codechain_core::miner::MinerService>::chain_new_blocks::hd6a80edf853db3c4
                        at core/src/miner/miner.rs:732
  13:     0x562090e51bf9 - codechain_core::client::importer::Importer::import_verified_blocks::ha5a3854c5eda42e2
                        at core/src/client/importer.rs:150
  14:     0x562090a264fe - codechain_core::client::client::Client::import_verified_blocks::h35d8db9a0bf8ccd1
                        at core/src/client/client.rs:213
  15:     0x562090af2956 - <codechain_core::service::ClientIoHandler as codechain_io::IoHandler<codechain_core::service::ClientIoMessage>>::message::h53ccf91adf84b0ae
                        at core/src/service.rs:95
  16:     0x562090a74551 - <codechain_io::service::IoChannel<Message>>::send_sync::h459884613492884a
                        at /home/sgkim126/workspace/kodebox/codechain/util/io/src/service.rs:399
  17:     0x562090e13d99 - codechain_core::verification::queue::QueueSignal::set_sync::h0a42193f9c314458
                        at core/src/verification/queue/mod.rs:97
  18:     0x562090b2aeaa - <codechain_core::verification::queue::VerificationQueue<K>>::verify::h7b47507c00bd1d60
                        at core/src/verification/queue/mod.rs:297
  19:     0x562090b28cd1 - <codechain_core::verification::queue::VerificationQueue<K>>::new::{{closure}}::h9862f706e4923889
                        at core/src/verification/queue/mod.rs:167
  20:     0x562090e62def - std::sys_common::backtrace::__rust_begin_short_backtrace::h1bf39baf982c5bbf
                        at /rustc/6c2484dc3c532c052f159264e970278d8b77cdc9/src/libstd/sys_common/backtrace.rs:135
  21:     0x562090dc0782 - std::thread::Builder::spawn_unchecked::{{closure}}::{{closure}}::hb3fe9523bd77671e
                        at /rustc/6c2484dc3c532c052f159264e970278d8b77cdc9/src/libstd/thread/mod.rs:469
  22:     0x562090e70d22 - <std::panic::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once::h29ab5b4ba66ddebe
                        at /rustc/6c2484dc3c532c052f159264e970278d8b77cdc9/src/libstd/panic.rs:309
  23:     0x562090e72186 - std::panicking::try::do_call::h12bb562d37ded902
                        at /rustc/6c2484dc3c532c052f159264e970278d8b77cdc9/src/libstd/panicking.rs:297
  24:     0x5620922cb499 - __rust_maybe_catch_panic
                        at src/libpanic_unwind/lib.rs:87
  25:     0x562090e71a2f - std::panicking::try::h326c2a89544fc7aa
                        at /rustc/6c2484dc3c532c052f159264e970278d8b77cdc9/src/libstd/panicking.rs:276
  26:     0x562090e70e62 - std::panic::catch_unwind::h41782e7179ae43cd
                        at /rustc/6c2484dc3c532c052f159264e970278d8b77cdc9/src/libstd/panic.rs:388
  27:     0x562090dbf35d - std::thread::Builder::spawn_unchecked::{{closure}}::h2b77fd9e35fb8566
                        at /rustc/6c2484dc3c532c052f159264e970278d8b77cdc9/src/libstd/thread/mod.rs:468
  28:     0x562090dc0c47 - <F as alloc::boxed::FnBox<A>>::call_box::h42601d6e6d8f3c55
                        at /rustc/6c2484dc3c532c052f159264e970278d8b77cdc9/src/liballoc/boxed.rs:749
  29:     0x5620922ca80d - call_once<(),()>
                        at /rustc/6c2484dc3c532c052f159264e970278d8b77cdc9/src/liballoc/boxed.rs:759
                         - start_thread
                        at src/libstd/sys_common/thread.rs:14
                         - thread_start
                        at src/libstd/sys/unix/thread.rs:81
  30:     0x7f1ceb3bd6da - start_thread
  31:     0x7f1ceaece88e - __clone
  32:                0x0 - <unknown>

Thread 'Verifier #2' panicked at 'Reseal min timer clear succeeds: TimerLoopDropped', src/libcore/result.rs:997

This is a bug. Please report it at:

    https://github.com/CodeChain-io/codechain/issues/new