Alerting: Jinja template evalutation of variables is broken on loops

[baldm]

What happened?

When setting a variable in a loop in the "Edit Routing Template" window, the variable in the loop is forgotten once the loop is exited.
An example of this can be seen with the code below

{% set flag = true %}
{% for alert in payload.alerts %}
    {# We set the flag to be false, to demonstrate it doesnt change outside the loop #}
    {% set flag = false %}
    {{ "Confirming we are in a loop." }}
{% endfor %}

{% if flag %}
    The flag is still true.
{% else %}
    The flag is false now.
{% endif %}

Gives the result:

X Confirming we are in a loop. The flag is still true.
Selected alert will not be matched with this route

What did you expect to happen?

The result should be:

X Confirming we are in a loop. The flag is false now.
Selected alert will not be matched with this route

As we set the variable to be false in the loop.

Did this work before?

I dont know

How do we reproduce it?

1. Copy code from example into the "Edit Routing Template" window.
2. Select a demo rule with 1 or more alerts in the alerts array. Any array to loop over instead of payload.alerts can be used.
3. Result is not the expected result

Is the bug inside a dashboard panel?

no

Environment (with versions)?

Grafana: Cloud
OS: MacOS
Browser: Firefox and Safari

Grafana platform?

I use Grafana Cloud

Datasource(s)?

No response

[Gunnnn]

I confirm this error. Here is workaround https://stackoverflow.com/questions/17925674/jinja2-local-global-variable#:~:text=You%20can%20use%20an%20array/dict%20like%20Miguel%20suggests%2C%20but%20you%20do%20not%20need%20the%20do%20extension%20per%20se%3B%20you%20can%20set%20a%20dummy%20var.%20I%20use%20the%20following%3A

[baldm]

i guess the error is with how Jinja evaluates scopes, and not with the Grafana implementation. I will close the issue.