[#2842] Update the main CKAN config object with the Flask specific keys

These were autogenerated or set during `make_flask_stack`, so they would
be lost when doing config.clear() (and updating with a previous copy, as
done extensively in the tests)

ckan/config/middleware/flask_app.py

@@ -32,6 +32,12 @@ def hello_world():
     def hello_world_post():
         return 'Hello World, this was posted to Flask'
 
+    # Update the main CKAN config object with the Flask specific keys
+    # that were set here or autogenerated
+    flask_config_keys = set(flask_app.config.keys()) - set(config.keys())
+    for key in flask_config_keys:
+        config[key] = flask_app.config[key]
+
     # Add a reference to the actual Flask app so it's easier to access
     app._wsgi_app = flask_app