general: save session at the very end (#47154)

It's necessary for native django responses as rendering will not go
through CompatWcsPublisher.

wcs/compat.py

@@ -228,6 +228,7 @@ class CompatWcsPublisher(WcsPublisher):
             # rendering may have altered it (for example a form would add its
             # token).
             self.session_manager.finish_successful_request()
+            request.ignore_session = True  # no further changes
 
         for name, value in response.generate_headers():
             if name in ('Connection', 'Content-Length'):

wcs/middleware.py

@@ -91,6 +91,13 @@ class PublisherInitialisationMiddleware(MiddlewareMixin):
     def process_response(self, request, response):
         pub = get_publisher()
         if pub:
+            request = pub.get_request()
+            if request and not request.ignore_session:
+                # it is necessary to save the session one last time as the actual
+                # rendering may have altered it (for example a form would add its
+                # token).
+                pub.session_manager.finish_successful_request()
+
             pub.cleanup()
         return response