Made order basket read only

src/oscar/apps/order/admin.py

     raw_id_fields = ['user', 'billing_address', 'shipping_address', ]
     list_display = ('number', 'total_incl_tax', 'site', 'user',
                     'billing_address', 'date_placed')
-    readonly_fields = ('number', 'total_incl_tax', 'total_excl_tax',
+    readonly_fields = ('number', 'basket', 'total_incl_tax', 'total_excl_tax',
                        'shipping_incl_tax', 'shipping_excl_tax')
     inlines = [LineInline]