Stable: Backports (#8986)

* snap: downgrade rust to revision 1.26.2, ref snapcraft/+bug/1778530 (#8984)

* snap: downgrade rust to revision 1.26.2, ref snapcraft/+bug/1778530

* snap: use plugin rust

* Fix deadlock in blockchain. (#8977)

* Remove js-glue from workspace

This fixes test error on Rust 1.27 but also prevents js-glue from building itself. Builtin dapp users can still use
js-glue from crates.io.

Cargo.toml

@@ -121,7 +121,6 @@ panic = "abort"
 [workspace]
 members = [
 	"chainspec",
-	"dapps/js-glue",
 	"ethcore/wasm/run",
 	"ethcore/types",
 	"ethkey/cli",

ethcore/src/blockchain/blockchain.rs

@@ -1425,18 +1425,24 @@ impl BlockChain {
 
 	/// Returns general blockchain information
 	pub fn chain_info(&self) -> BlockChainInfo {
+		// Make sure to call internal methods first to avoid
+		// recursive locking of `best_block`.
+		let first_block_hash = self.first_block();
+		let first_block_number = self.first_block_number().into();
+		let genesis_hash = self.genesis_hash();
+
 		// ensure data consistencly by locking everything first
 		let best_block = self.best_block.read();
 		let best_ancient_block = self.best_ancient_block.read();
 		BlockChainInfo {
 			total_difficulty: best_block.total_difficulty.clone(),
 			pending_total_difficulty: best_block.total_difficulty.clone(),
-			genesis_hash: self.genesis_hash(),
+			genesis_hash,
 			best_block_hash: best_block.hash,
 			best_block_number: best_block.number,
 			best_block_timestamp: best_block.timestamp,
-			first_block_hash: self.first_block(),
-			first_block_number: From::from(self.first_block_number()),
+			first_block_hash,
+			first_block_number,
 			ancient_block_hash: best_ancient_block.as_ref().map(|b| b.hash),
 			ancient_block_number: best_ancient_block.as_ref().map(|b| b.number),
 		}

snap/snapcraft.yaml

@@ -30,6 +30,8 @@ parts:
   parity:
     source: .
     plugin: rust
+  # rust-channel: stable  # @TODO enable after https://bugs.launchpad.net/snapcraft/+bug/1778530
+    rust-revision: 1.26.2 # @TODO remove after https://bugs.launchpad.net/snapcraft/+bug/1778530
     build-attributes: [no-system-libraries]
     build-packages: [g++, libudev-dev, libssl-dev, make, pkg-config]
     stage-packages: [libc6, libssl1.0.0, libudev1, libstdc++6]