Rococo Identity Migration Part 2 + Bug Fix (#2946)

Order:

- [x] Start People Chain
- [RPC
node](https://polkadot.js.org/apps/?rpc=wss%3A%2F%2Frococo-people-rpc.polkadot.io#/explorer)
- [x] Upgrade Rococo Relay (`EnsureRoot` -> `EnsureSigned`) (v1,006,002)
- Done
[here](https://rococo.subscan.io/extrinsic/0xef07e0f9dbb2b9e829305f132e6ce45d291239286e409177e20895e6687daa6c)
- [x] Migrate all identities
- Done, see extrinsics from [this
account](https://rococo.subscan.io/account/5FyNYrBwndvBttTkGUqGGCRAXtBH4Mh8xELDaxaFywTsjDKb)
- [x] Upgrade Rococo People (remove call filter) (v1,006,002)
- Authorized
[here](https://rococo.subscan.io/extrinsic/0xedf6a80229bd411b7ed8d3a489a767b0f773bed5c49239987a294c293a35b98b)

With added:

- [x] Upgrade Rococo People to fix `poke_deposit` bug (v1,006,001)
- Authorized
[here](https://rococo.subscan.io/extrinsic/0xd1dc3cd6e8274bd0196f8d9f13ed09f6e9c76e6a40f9786a1629f4cb22cf948d)

Note:

It's also possible to remove the Identity Migrator pallet from both the
Relay Chain and the parachain at this time. I will leave them in for now
to preserve the test cases until we run them on Kusama/Polkadot. We will
also want a follow up to remove all Identity-related state from the
Relay Chain.

substrate/frame/identity/src/lib.rs

@@ -1395,16 +1395,21 @@ impl<T: Config> Pallet<T> {
 			},
 		)?;
 
-		// Subs Deposit
-		let new_subs_deposit = SubsOf::<T>::try_mutate(
-			&target,
-			|(current_subs_deposit, subs_of)| -> Result<BalanceOf<T>, DispatchError> {
-				let new_subs_deposit = Self::subs_deposit(subs_of.len() as u32);
-				Self::rejig_deposit(&target, *current_subs_deposit, new_subs_deposit)?;
-				*current_subs_deposit = new_subs_deposit;
-				Ok(new_subs_deposit)
-			},
-		)?;
+		let new_subs_deposit = if SubsOf::<T>::contains_key(&target) {
+			SubsOf::<T>::try_mutate(
+				&target,
+				|(current_subs_deposit, subs_of)| -> Result<BalanceOf<T>, DispatchError> {
+					let new_subs_deposit = Self::subs_deposit(subs_of.len() as u32);
+					Self::rejig_deposit(&target, *current_subs_deposit, new_subs_deposit)?;
+					*current_subs_deposit = new_subs_deposit;
+					Ok(new_subs_deposit)
+				},
+			)?
+		} else {
+			// If the item doesn't exist, there is no "old" deposit, and the new one is zero, so no
+			// need to call rejig, it'd just be zero -> zero.
+			Zero::zero()
+		};
 		Ok((new_id_deposit, new_subs_deposit))
 	}