I had a weird failure which was caused by an unexpected disconnect and
reconnecct. Since we are prersistend and recover from these, they can
slip through our tests; most tests don't involve reconnection, so we
need to catch this explicitly.
For the connect() helper, we always suppress reconnection; tests which
want it all want other options so don't use this helper anyway. (Actually,
after I said that, test_closing_while_disconnected was added when I
rebased, which did require it, so I had to open-code that one).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>