Merge lp:~vila/bzr/686008-spurious-https-failure into lp:bzr

Catch spurious and bogus ssl TypeError exceptions.

This fixes bug #686008 by making sure we're not affected by bug
#637821 for python versions that didn't get spiv's patch. In
other words: in some cases, during cleanup of tests involving an
https server, we get a TypeError exception while trying to read a
closed ssl socket instead of a socket.error.

Various tests has been affected by this bug making selftest
itself unreliable since the failure was rarely on the same test
nor even the same platform.

I was able to trigger the bug with a test but unfortunately not
in a reproducible way :-/ It needed no less than 3 breakpoints,
some prints and a bit of luck...

Anyhow, the fix itself is reduced enough in scope that it should
never mask real failures (this occurs only during a test cleanup
and has no effect on test validity).

So the fix works but since I can't trigger it on demand (and it
has served its purpose which was to check the exception), I've
removed the test from the proposal, here it is for the curious:

class TestBug686008(tests.TestCase):

    _test_needs_features = [tests.HTTPSServerFeature]

    def test_it(self):
        from bzrlib.tests import https_server
        import ssl
        trigger_bug = False
        class RequestHandler(http_server.TestingHTTPRequestHandler):

            def handle_one_request(self):
                if trigger_bug:
                    # Now, break the ssl socket
                    sock = socket.socket(socket.AF_INET)
                    self.connection = ssl.wrap_socket(sock)
                    self.rfile = self.connection.makefile('rb', self.rbufsize)
                http_server.TestingHTTPRequestHandler.handle_one_request(self)

            def do_HEAD(self):
                # Always succeds, leaving the connection open
                self.close_connection = 0
                self.send_response(200)
                self.end_headers()

        server = https_server.HTTPSServer(RequestHandler)
        self.start_server(server)
        self.assertIsInstance(server.server,
                              https_server.TestingThreadingHTTPSServer)
        t = _urllib.HttpTransport_urllib(server.get_url())
        self.addCleanup(t.disconnect)
        # We need a first clean request
        t.has('foo')
        # Now we force the server to choke
        trigger_bug = True
        server.stop_server()