chore: fix clippy check failure (#1569)

tokio-executor/src/threadpool/pool/mod.rs

@@ -395,6 +395,7 @@ impl Pool {
 
     /// If there are any other workers currently relaxing, signal them that work
     /// is available so that they can try to find more work to process.
+    #[allow(clippy::cognitive_complexity)] // https://github.com/rust-lang/rust-clippy/issues/3900
     pub(crate) fn signal_work(&self, pool: &Arc<Pool>) {
         debug_assert_eq!(*self, **pool);
 

tokio-executor/src/threadpool/task/mod.rs

@@ -96,7 +96,7 @@ impl Task {
     /// scheduled again.
     ///
     // tracing macro expansion adds enough branches to make clippy angry here.
-    #[allow(clippy::cognitive_complexity)]
+    #[allow(clippy::cognitive_complexity)] // https://github.com/rust-lang/rust-clippy/issues/3900
     pub(crate) fn run(me: &Arc<Task>, pool: &Arc<Pool>) -> Run {
         use self::State::*;
         #[cfg(feature = "tracing")]

tokio-executor/src/threadpool/worker/mod.rs

@@ -564,7 +564,7 @@ impl Worker {
     ///
     /// Returns `true` if woken up due to new work arriving.
     // tracing macro expansion adds enough branches to make clippy angry here.
-    #[cfg_attr(feature = "tracing", allow(clippy::cognitive_complexity))]
+    #[allow(clippy::cognitive_complexity)] // https://github.com/rust-lang/rust-clippy/issues/3900
     fn sleep(&self) -> bool {
         use self::Lifecycle::*;