do not start spec_version guard when version mode is set to auto (#1278)

bridges/relays/bin-substrate/src/cli/mod.rs

@@ -528,6 +528,16 @@ macro_rules! declare_chain_options {
 			}
 
 			impl [<$chain ConnectionParams>] {
+				/// Returns `true` if version guard can be started.
+				///
+				/// There's no reason to run version guard when version mode is set to `Auto`. It can
+				/// lead to relay shutdown when chain is upgraded, even though we have explicitly
+				/// said that we don't want to shutdown.
+				#[allow(dead_code)]
+				pub fn can_start_version_guard(&self) -> bool {
+					self.[<$chain_prefix _runtime_version>].[<$chain_prefix _version_mode>] != RuntimeVersionType::Auto
+				}
+
 				/// Convert connection params into Substrate client.
 				pub async fn to_client<Chain: CliChain>(
 					&self,

bridges/relays/bin-substrate/src/cli/relay_headers.rs

@@ -157,7 +157,12 @@ impl RelayHeaders {
 				signer: target_sign,
 				mortality: target_transactions_mortality,
 			};
-			Finality::start_relay_guards(&target_client, &target_transactions_params);
+			Finality::start_relay_guards(
+				&target_client,
+				&target_transactions_params,
+				self.target.can_start_version_guard(),
+			)
+			.await?;
 
 			substrate_relay_helper::finality_pipeline::run::<Finality>(
 				source_client,

bridges/relays/bin-substrate/src/cli/relay_headers_and_messages.rs

@@ -512,11 +512,15 @@ impl RelayHeadersAndMessages {
 			LeftToRightFinality::start_relay_guards(
 				&right_client,
 				&left_to_right_transaction_params,
-			);
+				params.right.can_start_version_guard(),
+			)
+			.await?;
 			RightToLeftFinality::start_relay_guards(
 				&left_client,
 				&right_to_left_transaction_params,
-			);
+				params.left.can_start_version_guard(),
+			)
+			.await?;
 			let left_to_right_on_demand_headers = OnDemandHeadersRelay::new::<LeftToRightFinality>(
 				left_client.clone(),
 				right_client.clone(),