Index: tests/regressiontests/forms/tests.py
===================================================================
--- tests/regressiontests/forms/tests.py	(revision 4357)
+++ tests/regressiontests/forms/tests.py	(working copy)
@@ -2063,6 +2063,8 @@
 >>> f.clean_data
 {'username': u'adrian', 'password1': u'foo', 'password2': u'foo'}
 
+# Dynamic construction ########################################################
+
 It's possible to construct a Form dynamically by adding to the self.fields
 dictionary in __init__(). Don't forget to call Form.__init__() within the
 subclass' __init__().
@@ -2078,6 +2080,25 @@
 <tr><th>Last name:</th><td><input type="text" name="last_name" /></td></tr>
 <tr><th>Birthday:</th><td><input type="text" name="birthday" /></td></tr>
 
+Instances of a dynamic form should not persist fields from one
+form instance to the next
+>>> class MyForm(Form):
+...     def __init__(self, data=None, auto_id=False, field_list=[]):
+...         Form.__init__(self, data, auto_id)
+...         for field in field_list:
+...             self.fields[field[0]] = field[1]
+... 
+>>> field_list = ( ('field1', CharField()), ('field2', CharField()) )
+>>> my_form = MyForm(field_list=field_list)
+>>> print my_form
+<tr><th>Field1:</th><td><input type="text" name="field1" /></td></tr>
+<tr><th>Field2:</th><td><input type="text" name="field2" /></td></tr>
+>>> field_list = ( ('field3', CharField()), ('field4', CharField()) )
+>>> my_form = MyForm(field_list=field_list)
+>>> print my_form
+<tr><th>Field3:</th><td><input type="text" name="field3" /></td></tr>
+<tr><th>Field4:</th><td><input type="text" name="field4" /></td></tr>
+
 HiddenInput widgets are displayed differently in the as_table(), as_ul()
 and as_p() output of a Form -- their verbose names are not displayed, and a
 separate row is not displayed. They're displayed in the last row of the