Fixed #1104: set `FormWizard.extra_context` in `__init__` to avoid context leakage.

class FormWizard(object):

    # Dictionary of extra template context variables.

    extra_context = {}

    # The HTML (and POST data) field name for the "step" variable.

    step_field_name="wizard_step"

    # METHODS SUBCLASSES SHOULDN'T OVERRIDE ###################################

    def __init__(self, form_list, initial=None):

        "form_list should be a list of Form classes (not instances)."

        """

        Start a new wizard with a list of forms.

        form_list should be a list of Form classes (not instances).

        """

        self.form_list = form_list[:]

        self.initial = initial or {}

        self.step = 0 # A zero-based counter keeping track of which step we're in.

        # Dictionary of extra template context variables.

        extra_context = {}

        # A zero-based counter keeping track of which step we're in.

        self.step = 0 

    def __repr__(self):

        return "step: %d\nform_list: %s\ninitial_data: %s" % (self.step, self.form_list, self.initial)