Modfiy Gravity.sol to reserve event nonce 1

Now that we are emitting validator set update events with an event nonce
we have an event that is using event nonce zero. This is a big problem
on the Cosmos side as the logic has all been developed with the
assumption that event nonce 0 is a special unused value.

orchestrator/orchestrator/src/oracle_resync.rs

@@ -169,11 +169,11 @@ pub async fn get_last_checked_block(
                     // no other events can come before it, therefore either there's been a parsing error
                     // or no events have been submitted on this chain yet.
                     if valset.valset_nonce == 0 && last_event_nonce == 1u8.into() {
-                        return latest_block;
+                        return event.block_number.unwrap();
                     }
                     // if we're looking for a later event nonce and we find the deployment of the contract
                     // we must have failed to parse the event we're looking for. The oracle can not start
-                    if valset.valset_nonce == 0 && last_event_nonce > 1u8.into() {
+                    else if valset.valset_nonce == 0 && last_event_nonce > 1u8.into() {
                         panic!("Could not find the last event relayed by {}, Last Event nonce is {} but no event matching that could be found!", our_cosmos_address, last_event_nonce)
                     }
                 }
@@ -183,6 +183,8 @@ pub async fn get_last_checked_block(
         current_block = end_search;
     }
 
+    // we should exit above when we find the zero valset, if we have the wrong contract address through we could be at it a while as we go over
+    // the entire history to 'prove' it.
     panic!("You have reached the end of block history without finding the Gravity contract deploy event! You must have the wrong contract address!");
 }
 

solidity/contracts/Gravity.sol

@@ -35,7 +35,9 @@ contract Gravity is ReentrancyGuard {
 	mapping(address => uint256) public state_lastBatchNonces;
 	mapping(bytes32 => uint256) public state_invalidationMapping;
 	uint256 public state_lastValsetNonce = 0;
-	uint256 public state_lastEventNonce = 0;
+	// event nonce zero is reserved by the Cosmos module as a special
+	// value indicating that no events have yet been submitted
+	uint256 public state_lastEventNonce = 1;
 
 	// These are set once at initialization
 	bytes32 public state_gravityId;

solidity/test/deployERC20.ts

@@ -63,7 +63,7 @@ async function runTest(opts: {}) {
     _name: 'Atom',
     _symbol: 'ATOM',
     _decimals: 6,
-    _eventNonce: BigNumber.from(1)
+    _eventNonce: BigNumber.from(2)
   })
 
 

solidity/test/sendToCosmos.ts

@@ -45,11 +45,11 @@ async function runTest(opts: {}) {
       await signers[0].getAddress(),
       ethers.utils.formatBytes32String("myCosmosAddress"),
       1000, 
-      1
+      2
     );
 
   expect((await testERC20.functions.balanceOf(gravity.address))[0]).to.equal(1000);
-  expect((await gravity.functions.state_lastEventNonce())[0]).to.equal(1);
+  expect((await gravity.functions.state_lastEventNonce())[0]).to.equal(2);
 
 
 
@@ -65,11 +65,11 @@ async function runTest(opts: {}) {
       await signers[0].getAddress(),
       ethers.utils.formatBytes32String("myCosmosAddress"),
       1000, 
-      2
+      3
     );
 
   expect((await testERC20.functions.balanceOf(gravity.address))[0]).to.equal(2000);
-  expect((await gravity.functions.state_lastEventNonce())[0]).to.equal(2);
+  expect((await gravity.functions.state_lastEventNonce())[0]).to.equal(3);
 }
 
 describe("sendToCosmos tests", function () {