"action=raw" doesn't work on the page namespace of Wikisource.
Steps to reproduce:
- Go to the following link and start the download: https://eo.wikisource.org/w/index.php?title=Paĝo:Mirinda_amo.pdf/18&action=raw
- Open the file and see that it's empty
- Now check https://eo.wikisource.org/w/index.php?title=Paĝo:Mirinda_amo.pdf/18&action=edit and see that there is actually content there