Use correct daemon API

server/daemon.py

@@ -128,6 +128,10 @@ class Daemon(util.LoggedClass):
         params_iterable = ((h, ) for h in range(first, first + count))
         return await self._send_vector('getblockhash', params_iterable)
 
+    async def deserialised_block(self, hex_hash):
+        '''Return the deserialised block with the given hex hash.'''
+        return await self._send_single('getblock', (hex_hash, True))
+
     async def raw_blocks(self, hex_hashes):
         '''Return the raw binary blocks with the given hex hashes.'''
         params_iterable = ((h, False) for h in hex_hashes)

server/protocol.py

@@ -382,8 +382,8 @@ class ElectrumX(JSONRPC):
     @classmethod
     async def tx_merkle(cls, tx_hash, height):
         '''tx_hash is a hex string.'''
-        block_hash = await cls.DAEMON.send_single('getblockhash', (height,))
-        block = await cls.DAEMON.send_single('getblock', (block_hash, True))
+        hex_hashes = await cls.DAEMON.block_hex_hashes(height, 1)
+        block = await cls.DAEMON.deserialised_block(hex_hashes[0])
         tx_hashes = block['tx']
         # This will throw if the tx_hash is bad
         pos = tx_hashes.index(tx_hash)