[1.6.x] Refs #23964 -- Added warning about case-insensitive, unique fields used with formsets

.. _MySQL Unicode Character Sets: http://dev.mysql.com/doc/refman/5.7/en/charset-unicode-sets.html

.. warning::

    Model formsets validate unique fields in a case-sensitive manner. Thus when

    using a case-insensitive collation, a formset with unique field values that

    differ only by case will pass validation, but upon calling ``save()``, an

    ``IntegrityError`` will be raised.

Connecting to the database

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