pytest: Add test for issue 1737 that is expected to fail

This reproduces the issue described in issue #1737 and will be fixed by the next
commit.

tests/test_rpc.py

@@ -0,0 +1,38 @@
+from fixtures import *  # noqa: F401,F403
+
+import os
+import pytest
+import signal
+import unittest
+
+with open('config.vars') as configfile:
+    config = dict([(line.rstrip().split('=', 1)) for line in configfile])
+
+DEVELOPER = os.getenv("DEVELOPER", config['DEVELOPER']) == "1"
+
+
+@pytest.mark.xfail(strict=True)
+@unittest.skipIf(not DEVELOPER, "needs --dev-disconnect")
+def test_stop_pending_fundchannel(node_factory, executor):
+    """Stop the daemon while waiting for an accept_channel
+
+    This used to crash the node, since we were calling unreserve_utxo while freeing
+    the daemon, but that needs a DB transaction to be open.
+    """
+    l1 = node_factory.get_node()
+    l2 = node_factory.get_node()
+
+    l1.rpc.connect(l2.info['id'], 'localhost', l2.port)
+
+    # We want l2 to stop replying altogether, not disconnect
+    os.kill(l2.daemon.proc.pid, signal.SIGSTOP)
+
+    # The fundchannel call will not terminate so run it in a future
+    executor.submit(l1.fund_channel, l2, 10**6)
+    l1.daemon.wait_for_log('peer_out WIRE_OPEN_CHANNEL')
+
+    l1.rpc.stop()
+
+    # Now allow l2 a clean shutdown
+    os.kill(l2.daemon.proc.pid, signal.SIGCONT)
+    l2.rpc.stop()