message: [Consensus] SyncManager - import std::Result instead of failure::Result
  This seem to make more sense, as std::Result is used more often.
diff: @@ -15,12 +15,13 @@ use crate::{
  util::mutex_map::MutexMap,
  };
  use crypto::HashValue;
  -use failure::{Fail, Result};
  +use failure::{self, Fail};
  use logger::prelude::*;
  use network::proto::BlockRetrievalStatus;
  use rand::{prelude::*, Rng};
  use std::{
  clone::Clone,
  + result::Result,
  sync::Arc,
  time::{Duration, Instant},
  };
  @@ -77,7 +78,7 @@ where
  /// Fetches dependencies for given sync_info.quorum_cert
  /// If gap is large, performs state sync using process_highest_ledger_info
  /// Inserts sync_info.quorum_cert into block store as the last step
  - pub async fn sync_to(&mut self, deadline: Instant, sync_info: SyncInfo) -> Result<()> {
  + pub async fn sync_to(&mut self, deadline: Instant, sync_info: SyncInfo) -> failure::Result<()> {
  let highest_ledger_info = sync_info.highest_ledger_info.clone();
  self.process_highest_ledger_info(highest_ledger_info, sync_info.peer, deadline)
  @@ -98,7 +99,7 @@ where
  start_version: u64,
  target_version: u64,
  batch_size: u64,
  - ) -> Result<TransactionListWithProof> {
  + ) -> failure::Result<TransactionListWithProof> {
  self.state_computer
  .get_chunk(start_version, target_version, batch_size)
  .await
  @@ -107,7 +108,7 @@ where
  pub async fn execute_and_insert_block(
  &self,
  block: Block<T>,
  - ) -> std::result::Result<Arc<Block<T>>, InsertError> {
  + ) -> Result<Arc<Block<T>>, InsertError> {
  let _guard = self.block_mutex_map.lock(block.id());
  // execute_and_insert_block has shortcut to return block if it exists
  self.block_store.execute_and_insert_block(block).await
  @@ -122,7 +123,7 @@ where
  qc: QuorumCert,
  preferred_peer: Author,
  deadline: Instant,
  - ) -> std::result::Result<(), InsertError> {
  + ) -> Result<(), InsertError> {
  let mut lock_set = self.block_mutex_map.new_lock_set();
  let mut pending = vec![];
  let network = self.network.clone();
  @@ -179,7 +180,7 @@ where
  highest_ledger_info: QuorumCert,
  peer: Author,
  deadline: Instant,
  - ) -> Result<()> {
  + ) -> failure::Result<()> {
  let committed_block_id = highest_ledger_info
  .committed_block_id()
  .ok_or_else(|| format_err!("highest ledger info has no committed block"))?;
  @@ -289,7 +290,7 @@ impl BlockRetriever {
  &'a mut self,
  qc: &'a QuorumCert,
  num_blocks: u64,
  - ) -> std::result::Result<Vec<Block<T>>, BlockRetrieverError>
  + ) -> Result<Vec<Block<T>>, BlockRetrieverError>
  where
  T: Payload,
  {
  