I don't know if it has already been reported?
On the page (https://download.supertux.org/) to download the nightly version of supertux for windows, be it 32 or 64 bits, it is not working, it is not downloading and the code in the source tab is empty.
When I click to download it gives an error "This XML file does not appear to have any style information associated with it. The document tree is shown below.".