Don't sort keys by default in tojson when rendering profile forms

jinja2's tojson sorts keys in dicts by default. This was useful
in the time when python's dicts were not ordered. However, now that
dicts are ordered in python, this screws it up. Since profiles are
dicts, ordering *does* matter - they should be displayed to the user
in the order that the admin sets them. This allows template writers
to use `|tojson` on the profile_list (to be read by JS)
without worrying about ordering getting mangled. Template writers
can still sort keys by explicitly using `|dictsort` in their
template

kubespawner/spawner.py

@@ -2936,6 +2936,18 @@ def _render_options_form(self, profile_list):
         )
 
         env = Environment(loader=loader)
+
+        # jinja2's tojson sorts keys in dicts by default. This was useful
+        # in the time when python's dicts were not ordered. However, now that
+        # dicts are ordered in python, this screws it up. Since profiles are
+        # dicts, ordering *does* matter - they should be displayed to the user
+        # in the order that the admin sets them. This allows template writers
+        # to use `|tojson` on the profile_list (to be read by JS)
+        # without worrying about ordering getting mangled. Template writers
+        # can still sort keys by explicitly using `|dictsort` in their
+        # template
+        env.policies['json.dumps_kwargs'] = {'sort_keys': False}
+
         if self.profile_form_template != "":
             profile_form_template = env.from_string(self.profile_form_template)
         else: