Add a test for 'fundchannel_start' crash on deconnection

tests/test_connection.py

@@ -920,6 +920,7 @@ def test_funding_cancel_race(node_factory, bitcoind, executor):
 def test_funding_external_wallet(node_factory, bitcoind):
     l1 = node_factory.get_node()
     l2 = node_factory.get_node()
+    l3 = node_factory.get_node()
 
     l1.rpc.connect(l2.info['id'], 'localhost', l2.port)
     assert(l1.rpc.listpeers()['peers'][0]['id'] == l2.info['id'])
@@ -966,6 +967,11 @@ def test_funding_external_wallet(node_factory, bitcoind):
         channel = node.rpc.listpeers()['peers'][0]['channels'][0]
         assert amount * 1000 == channel['msatoshi_total']
 
+    # Test that we don't crash if peer disconnects after fundchannel_start
+    l2.connect(l3)
+    l2.rpc.fundchannel_start(l3.info["id"], amount)
+    l3.rpc.close(l2.info["id"])
+
 
 def test_lockin_between_restart(node_factory, bitcoind):
     l1 = node_factory.get_node(may_reconnect=True)