Check for failed transactions due to double spends

[ssadler]

zeno/src/Network/Bitcoin.hs

Lines 58 to 68 in fa13a8f

	bitcoinSubmitTxSync :: Has BitcoinConfig r => Int -> SaplingTx -> Zeno r H.TxHash
	bitcoinSubmitTxSync confirmations tx = do
	txid <- queryBitcoin "sendrawtransaction" [tx]
	fix $ \f -> do
	threadDelay 5000000
	rawtx <- queryBitcoin "getrawtransaction" (txid, 1::Int)
	case rawtx .? "{confirmations}" of
	Nothing -> f
	Just (n::Int) -> if n < confirmations then f else pure txid

There's currently a possibility for the submit to return OK, but then a double spend to occur (accidentally or otherwise) and take out one of the inputs. getrawtransaction won't indicate that there's a problem in this case, so it'll loop forever. This should be made more robust, by repeatedly calling submitrawtransaction, or some other way, that would give indication in the case of a double spend.