Add local cluster tests that broadcast duplicate slots (#13995)

* Add duplicate node local cluster test

* fix clippy

* remove dupe test

runtime/src/blockhash_queue.rs

@@ -127,7 +127,7 @@ impl BlockhashQueue {
             .map(|(k, v)| recent_blockhashes::IterItem(v.hash_height, k, &v.fee_calculator))
     }
 
-    pub fn len(&self) -> usize {
+    pub(crate) fn len(&self) -> usize {
         self.max_age
     }
 }

runtime/src/lib.rs

@@ -12,7 +12,7 @@ pub mod bank;
 pub mod bank_client;
 pub mod bank_forks;
 pub mod bank_utils;
-mod blockhash_queue;
+pub mod blockhash_queue;
 pub mod bloom;
 pub mod builtins;
 pub mod commitment;