V2.5.6 stable (#10961)

-  Fix cargo audit (#10921)
  - Add support for Energy Web Foundation's new chains (#10957)
  - Kaspersky AV whitelisting (#10919)
  - Avast whitelist script (#10900)
  - Docker images renaming (#10863)
  - Remove excessive warning (#10831)
  - Allow --nat extip:your.host.here.org (#10830)
  - When updating the client or when called from RPC, sleep should mean sleep (#10814)
  - added new ropsten-bootnode and removed old one (#10794)
  - ethkey no longer uses byteorder (#10786)
  - Do not drop the peer with None difficulty (#10772)
  - docs: Update Readme with TOC, Contributor Guideline. Update Cargo package descriptions (#10652)

ethcore/sync/Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-description = "Ethcore blockchain sync"
+description = "Parity Ethereum (EthCore) Blockchain Synchronization (Strategy, Blockchain Downloader, Blockchain Synchronization Implementation of Ethereum Protocol, Propagating Data to Peers, Requesting Data from Peers, Supplying Data in Response to Peer Requests, Handling Peer Responses, Matching Packet IDs and Protocol, Light Client Synchronization of Header Chain, Header Download State Machine, Light Decoding & Verifying Header Responses, Private Transaction Handling, Synchronization Snapshot Service to Download & Verify Block Chunks, Peer Connection Management and Blockchain Client I/O Interface for Synchronization Handler, Transaction Statistics)"
 name = "ethcore-sync"
 version = "1.12.0"
 license = "GPL-3.0"

ethcore/sync/src/chain/mod.rs

@@ -962,7 +962,7 @@ impl ChainSync {
 					}
 
 					// Only ask for old blocks if the peer has an equal or higher difficulty
-					let equal_or_higher_difficulty = peer_difficulty.map_or(false, |pd| pd >= syncing_difficulty);
+					let equal_or_higher_difficulty = peer_difficulty.map_or(true, |pd| pd >= syncing_difficulty);
 
 					if force || equal_or_higher_difficulty {
 						if let Some(request) = self.old_blocks.as_mut().and_then(|d| d.request_blocks(peer_id, io, num_active_peers)) {