I've started seeing weird behaviour in tests since i upgraded to v 2.40 of the Python
bindings.  It doesn't happen in 2.39.

(Ubuntu 13.10, Firefox)

here's the basic code:

self.browser.find_element_by_link_text('Reticulate splines').click()
self.assertEqual(self.browser.current_url, first_list_url)

Essentially, this expects the URL to change after we click a link.  It's a normal link,
no javascript magic.

Now, I understand there may be a race condition here, there's no guarantee that the
page load that's triggered by the click will have completed by the time I ask for the
browser.current_url.  I found it tended to always work locally, but would sometimes
fail under jenkins CI.

So I built a little wait loop:

        self.browser.find_element_by_link_text('Reticulate splines').click()
        self.wait_for(
            lambda: self.assertEqual(self.browser.current_url, first_list_url)
        )


[...]

    def wait_for(self, function_with_assertion, timeout=DEFAULT_WAIT):
        start_time = time.time()
        while time.time() - start_time < timeout:
            try:
                time.sleep(0.2)  # sleep first to let things settle
                return function_with_assertion()
            except (AssertionError, WebDriverException):
                pass
        # one more try, which will raise any errors if they are outstanding
        return function_with_assertion()

And that works, both locally and on jenkins.  But once I upgraded to selenium 2.40,
it started failing again.  It looks like the click just wasn't going through.

Some things I've tried:

- switching to PhantomJS.  that produced an intriguing error, on the click that precedes
the browser url check, saying "click succeeded but load failed"... that seemed relevant
perhaps?

- i worried that the call to browser.currrent_url was happening too soon after the
click, so it was somehow interrupting it. i put a time.sleep after.  no dice.

- i tried adding a little retry loop, where it tries to click a second time. that works.
 but it kinda sucks.

- i tried taking screenshots.  a basic selenium screenshot show the page with the link
hover active, but stuck on the page with the link.  a full os screenshot shows the
little link-hover-url-thingy.  that click is definitely hanging somehow.

- i'm using the latest selenium (2.40)
- i'm using the latest firefox (27.0.1)
- i'm using xvfb both locally and on the server, so that's not it
- i thought it might be server-side:  the server is spawned in a thread by django liveservertestcase.
 i set the test to run against a separate staging server instead.  the error still
occurs.

I've had a bit of a try at producing a minimal repro, but no dice.  it only seems to
affect one test out of 6 in my test suite.  my repo *is* publicly available though,
so feel free to use it to try and repro:

https://github.com/hjwp/book-example/tree/chapter_19

to run the failing test:

python3 manage.py test functional_tests.test_my_lists