fix: the occasional staking module `SimulateMsgCancelUnbondingDelegat…

…e` failure (backport cosmos#12933) (cosmos#12962)

x/staking/simulation/operations.go

@@ -410,8 +410,22 @@ func SimulateMsgCancelUnbondingDelegate(ak types.AccountKeeper, bk types.BankKee
 			return simtypes.NoOpMsg(types.ModuleName, types.TypeMsgCancelUnbondingDelegation, "account does have any unbonding delegation"), nil, nil
 		}
 
-		// get random unbonding delegation entry at block height
-		unbondingDelegationEntry := unbondingDelegation.Entries[r.Intn(len(unbondingDelegation.Entries))]
+		// This is a temporary fix to make staking simulation pass. We should fetch
+		// the first unbondingDelegationEntry that matches the creationHeight, because
+		// currently the staking msgServer chooses the first unbondingDelegationEntry
+		// with the matching creationHeight.
+		//
+		// ref: https://github.com/cosmos/cosmos-sdk/issues/12932
+		creationHeight := unbondingDelegation.Entries[r.Intn(len(unbondingDelegation.Entries))].CreationHeight
+
+		var unbondingDelegationEntry types.UnbondingDelegationEntry
+
+		for _, entry := range unbondingDelegation.Entries {
+			if entry.CreationHeight == creationHeight {
+				unbondingDelegationEntry = entry
+				break
+			}
+		}
 
 		if unbondingDelegationEntry.CompletionTime.Before(ctx.BlockTime()) {
 			return simtypes.NoOpMsg(types.ModuleName, types.TypeMsgCancelUnbondingDelegation, "unbonding delegation is already processed"), nil, nil