disable admin ability to change usernames
@@ -14,6 +14,7 @@ class UserCreationFormExtended(UserCreationForm):
self.fields['email'] = forms.EmailField(label=_("E-mail"), max_length=75)
UserAdmin.add_form = UserCreationFormExtended
+UserAdmin.readonly_fields = ('username',)
UserAdmin.add_fieldsets = (
(None, {
'classes': ('wide',),
