refactor: remove unnecessary decrement when fast forwarding upgrade s…

…equence (#5231)

* update ChanUpgradeTry function

* update with Aditya's suggestion

* update with Carlos's review

* add check in test

* refactor: remove unnecessary - 1 on fast forward

---------

Co-authored-by: Charly <charly@interchain.berlin>
Co-authored-by: Đỗ Việt Hoàng <hoangdv2429@gmail.com>
Co-authored-by: Colin Axnér <25233464+colin-axner@users.noreply.github.com>

modules/core/04-channel/keeper/upgrade.go

@@ -118,20 +118,19 @@ func (k Keeper) ChanUpgradeTry(
 	if found {
 		proposedUpgradeFields = upgrade.Fields
 	} else {
-		// if the counterparty sequence is greater than the current sequence, we fast-forward to the counterparty sequence.
-		if counterpartyUpgradeSequence > channel.UpgradeSequence {
-			// using -1 as WriteUpgradeInitChannel increments the sequence
-			channel.UpgradeSequence = counterpartyUpgradeSequence - 1
-			k.SetChannel(ctx, portID, channelID, channel)
-		}
-
 		// NOTE: OnChanUpgradeInit will not be executed by the application
 		upgrade, err = k.ChanUpgradeInit(ctx, portID, channelID, proposedUpgradeFields)
 		if err != nil {
 			return types.Channel{}, types.Upgrade{}, errorsmod.Wrap(err, "failed to initialize upgrade")
 		}
 
-		channel, upgrade = k.WriteUpgradeInitChannel(ctx, portID, channelID, upgrade, proposedUpgradeFields.Version)
+		channel, upgrade = k.WriteUpgradeInitChannel(ctx, portID, channelID, upgrade, upgrade.Fields.Version)
+
+		// if the counterparty sequence is greater than the current sequence, we fast-forward to the counterparty sequence.
+		if counterpartyUpgradeSequence > channel.UpgradeSequence {
+			channel.UpgradeSequence = counterpartyUpgradeSequence
+			k.SetChannel(ctx, portID, channelID, channel)
+		}
 	}
 
 	if err := k.checkForUpgradeCompatibility(ctx, proposedUpgradeFields, counterpartyUpgradeFields); err != nil {

modules/core/04-channel/keeper/upgrade_test.go

@@ -300,6 +300,7 @@ func (suite *KeeperTestSuite) TestChanUpgradeTry() {
 				suite.Require().NoError(err)
 				suite.Require().NotEmpty(upgrade)
 				suite.Require().Equal(proposedUpgrade.Fields, upgrade.Fields)
+				suite.Require().Equal(path.EndpointA.GetChannel().UpgradeSequence, path.EndpointB.GetChannel().UpgradeSequence)
 			} else {
 				suite.assertUpgradeError(err, tc.expError)
 			}