Rename double vote variable

Some DoubleVote type variables should be renamed for consistency.

Author: Byeongjee Kang

core/src/consensus/tendermint/worker.rs

@@ -1430,9 +1430,9 @@ impl Worker {
                 self.votes_received.set(vote_index);
             }
 
-            if let Err(double) = self.votes.collect(message.clone()) {
-                cerror!(ENGINE, "Double vote found {:?}", double);
-                self.report_double_vote(&double);
+            if let Err(double_vote) = self.votes.collect(message.clone()) {
+                cerror!(ENGINE, "Double vote found {:?}", double_vote);
+                self.report_double_vote(&double_vote);
                 return Err(EngineError::DoubleVote(sender))
             }
             ctrace!(ENGINE, "Handling a valid {:?} from {}.", message, sender);
@@ -1823,9 +1823,9 @@ impl Worker {
                 );
             }
 
-            if let Err(double) = self.votes.collect(message) {
-                cerror!(ENGINE, "Double Vote found {:?}", double);
-                self.report_double_vote(&double);
+            if let Err(double_vote) = self.votes.collect(message) {
+                cerror!(ENGINE, "Double Vote found {:?}", double_vote);
+                self.report_double_vote(&double_vote);
                 return None
             }
         }