Python Class Members Initialization
What you keep referring to as a bug is the documented, standard behavior of Python classes.
Declaring a dict outside of __init__ as you initially did is declaring a class-level variable. It is only created once at first, whenever you create new objects it will reuse this same dict. To create instance variables, you declare them with self in __init__; its as simple as that.
When you access attribute of instance, say, self.foo, python will first find 'foo' in self.__dict__. If not found, python will find 'foo' in TheClass.__dict__
In your case, dict1 is of class A, not instance.
@Matthew : Please review the difference between a class member and an object member in Object Oriented Programming. This problem happens because of the declaration of the original dict makes it a class member, and not an object member (as was the original poster's intent.) Consequently, it exists once for (is shared accross) all instances of the class (ie once for the class itself, as a member of the class object itself) so the behaviour is perfectly correct.