Fix intermittent test failures due to missing sync_all

test/functional/wallet_send.py

@@ -503,6 +503,7 @@ class WalletSendTest(BitcoinTestFramework):
         self.nodes[0].sendtoaddress(addr, 10)
         self.nodes[0].sendtoaddress(ext_wallet.getnewaddress(), 10)
         self.generate(self.nodes[0], 6)
+        self.sync_all()
         ext_utxo = ext_fund.listunspent(addresses=[addr])[0]
 
         # An external input without solving data should result in an error