rpc: add one to the block height for the getblockcount response

There is a difference in interpretation of what a block count is. neo-go nodes
currently respond to this request with the latest block number which is the
same number that neoscan.io shows. However, C# nodes deliberately do add one
to this number when answering to the getblockcount request to account for the
genesis block number 0.

This patch makes us consistent with C# nodes wrt to getblockcount behaviour.

pkg/rpc/server.go

@@ -157,7 +157,7 @@ Methods:
 		results = wrappers.NewBlock(block, s.chain)
 	case "getblockcount":
 		getblockcountCalled.Inc()
-		results = s.chain.BlockHeight()
+		results = s.chain.BlockHeight() + 1
 
 	case "getblockhash":
 		getblockHashCalled.Inc()

pkg/rpc/server_test.go

@@ -51,7 +51,7 @@ func TestRPC(t *testing.T) {
 		var res IntResultResponse
 		err := json.Unmarshal(bytes.TrimSpace(body), &res)
 		assert.NoErrorf(t, err, "could not parse response: %s", body)
-		assert.Equal(t, chain.BlockHeight(), uint32(res.Result))
+		assert.Equal(t, chain.BlockHeight()+1, uint32(res.Result))
 	})
 
 	t.Run("getblockhash", func(t *testing.T) {