JSONField has_changed doesn't reflect disabled correctly

[alex]

Problem:

A disabled JSONField still reports changes via has_changed.

Why?

` python
def has_changed(self, initial, data):

# here we miss the check for disabled
if super().has_changed(initial, data):

return True

...

`
As we see, has_changed from the base is called and if successful, True is returned. But we have no additional check for disabled.

Fix:

` python
def has_changed(self, initial, data):

if self.disabled:

return False

if super().has_changed(initial, data):

return True

...

`

This corrupts the changed fields in the history of admin.