fix migration

frame/fast-unstake/src/benchmarking.rs

@@ -44,11 +44,13 @@ fn l<T: Config>(
 }
 
 fn create_unexposed_nominators<T: Config>() -> Vec<T::AccountId> {
-	(0..T::BatchSize::get()).map(|i| {
-		let account = frame_benchmarking::account::<T::AccountId>("nominator_42", i, USER_SEED);
-		fund_and_bond_account::<T>(&account);
-		account
-	}).collect()
+	(0..T::BatchSize::get())
+		.map(|i| {
+			let account = frame_benchmarking::account::<T::AccountId>("nominator_42", i, USER_SEED);
+			fund_and_bond_account::<T>(&account);
+			account
+		})
+		.collect()
 }
 
 fn fund_and_bond_account<T: Config>(account: &T::AccountId) {

frame/fast-unstake/src/lib.rs

@@ -201,6 +201,29 @@ pub mod pallet {
 				return Weight::from_ref_time(0)
 			}
 
+			// Temporary for migration.
+			if Head::<T>::exists() && Head::<T>::get().is_none() {
+				// Migrate head.
+				let key = Head::<T>::hashed_key();
+				let (stash, deposit) = match frame_support::storage::unhashed::get::<(
+					T::AccountId,
+					Vec<EraIndex>,
+					BalanceOf<T>,
+				)>(&key)
+				.defensive()
+				{
+					Some((stash, _, deposit)) => (stash, deposit),
+					None => {
+						Head::<T>::kill();
+						return T::DbWeight::get().reads_writes(1, 1)
+					},
+				};
+				// insert them back into the queue.
+				Queue::<T>::insert(stash, deposit);
+				Head::<T>::kill();
+				return T::DbWeight::get().reads_writes(1, 2)
+			}
+
 			Self::do_on_idle(remaining_weight)
 		}
 	}

frame/fast-unstake/src/types.rs

@@ -41,5 +41,3 @@ pub struct UnstakeRequest<T: Config> {
 	/// The list of eras for which they have been checked.
 	pub(crate) checked: BoundedVec<EraIndex, MaxChecking<T>>,
 }
-
-// TODO: If we fail at reading the head, we should just remove it.