lightningd: don't complain about bad funding PSBT for elements.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

lightningd/opening_control.c

@@ -1031,9 +1031,11 @@ static struct command_result *json_fundchannel_complete(struct command *cmd,
 			return command_fail(cmd, FUNDING_PSBT_INVALID,
 					    "No output to open channel");
 
-		if (!amount_sat_eq(amount_sat(funding_psbt->tx->outputs
-					      [*funding_txout_num].satoshi),
-				   fc->funding))
+		/* Can't really check amounts for elements. */
+		if (!chainparams->is_elements
+		    && !amount_sat_eq(amount_sat(funding_psbt->tx->outputs
+						 [*funding_txout_num].satoshi),
+				      fc->funding))
 			return command_fail(cmd, FUNDING_PSBT_INVALID,
 					    "Output to open channel is %"PRIu64"sat,"
 					    " should be %s",

tests/test_connection.py

@@ -1094,11 +1094,12 @@ def test_funding_external_wallet_corners(node_factory, bitcoind):
     with pytest.raises(RpcError, match=r'Already funding channel'):
         l1.rpc.fundchannel(l2.info['id'], amount)
 
-    # Can't complete with incorrect amount.
-    wrongamt = l1.rpc.txprepare([{start['funding_address']: amount - 1}])
-    with pytest.raises(RpcError, match=r'Output to open channel is .*, should be .*'):
-        l1.rpc.fundchannel_complete(l2.info['id'], wrongamt['psbt'])
-    l1.rpc.txdiscard(wrongamt['txid'])
+    # Can't complete with incorrect amount (unchecked on Elements)
+    if TEST_NETWORK == 'regtest':
+        wrongamt = l1.rpc.txprepare([{start['funding_address']: amount - 1}])
+        with pytest.raises(RpcError, match=r'Output to open channel is .*, should be .*'):
+            l1.rpc.fundchannel_complete(l2.info['id'], wrongamt['psbt'])
+        l1.rpc.txdiscard(wrongamt['txid'])
 
     # Can't complete with incorrect address.
     wrongaddr = l1.rpc.txprepare([{l1.rpc.newaddr()['bech32']: amount}])