Refund leases that have not started. (#206)

Needed for a smooth migration to Coretime.

---------

Co-authored-by: eskimor <eskimor@no-such-url.com>
Co-authored-by: joe petrowski <25483142+joepetrowski@users.noreply.github.com>
Co-authored-by: Bastian Köcher <git@kchr.de>

CHANGELOG.md

@@ -14,6 +14,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Feature for enabling debug prints in the Polkadot and Kusama runtime ([polkadot-fellows/runtimes#85](https://github.com/polkadot-fellows/runtimes/pull/85))
 - Added new "Wish for Change" track ([polkadot-fellows/runtimes#184](https://github.com/polkadot-fellows/runtimes/pull/184))
 - Enable Coretime and on-demand on Kusama ([polkadot-fellows/runtimes#159](https://github.com/polkadot-fellows/runtimes/pull/159))
+- Refund any leases that are not migrated to Coretime (have holes in them/have not yet started) ([polkadot-fellows/runtimes#206](https://github.com/polkadot-fellows/runtimes/pull/206))
 - Enable Elastic Scaling node side feature for Kusama ([polkadot-fellows/runtimes#205](https://github.com/polkadot-fellows/runtimes/pull/205))
 - Cancel Parachain Auctions ([polkadot-fellows/runtimes#215](https://github.com/polkadot-fellows/runtimes/pull/215))
 

relay/kusama/src/lib.rs

@@ -1764,8 +1764,19 @@ pub mod migrations {
 			if lease.is_empty() {
 				return None
 			}
-			// Lease not yet started, ignore:
+			// Lease not yet started/or having holes, refund (coretime can't handle this):
 			if lease.iter().any(Option::is_none) {
+				if let Err(err) = slots::Pallet::<Runtime>::clear_all_leases(
+					frame_system::RawOrigin::Root.into(),
+					para,
+				) {
+					log::error!(
+						target: "runtime",
+						"Clearing lease for para: {:?} failed, with error: {:?}",
+						para,
+						err
+					);
+				};
 				return None
 			}
 			let (index, _) =