Fixed #7060 -- Added a note about race conditions to the tutorial

results page that gets updated each time you vote. If you submit the form

without having chosen a choice, you should see the error message.

.. note::

    The code for our ``vote()`` view does have a small problem. It first gets

    the ``selected_choice`` object from the database, then computes the new

    value of ``votes``, and then saves it back to the database. If two users of

    your Web site try to vote at *exactly the same time*, this might go wrong:

    The same value, let's say 42, will be retrieved for ``votes``. Then, for

    both users the new value of 43 is computed and saved, but 44 would be the

    expected value.

    This is called a *race condition*. If you are interested, you can read

    :ref:`avoiding-race-conditions-using-f` to learn how you can solve this

    issue.

Use generic views: Less code is better

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