url_for not allow to use custom scheme (webcal)

[gebeto]

I need to generate external URL for my ICS subscription, in this case I need to use some custom protocol: webcal://, but when I'm trying to use it, it is falling back to http which is really annoying, because it not allow to use any other protocol, only "http" or "https" which I think, is not really correct

I see the issue, according to the code, it is assigning "https" to the variable if that variable is "https", why?:

https://github.com/pallets/werkzeug/blob/main/src/werkzeug/routing/map.py#L935-L941

It looks like everything will work the same if we will just remove that assignment, and it will just allow to use custom scheme