[bug] .ai file automatically converted to pdf on donwload

[Xyleme-git]

Description of the bug

Hi & Thanks @mickael-kerjean for creating Filestash :)
I have an issue with .ai files. I upload .ai files on my share. When I then download it, they are automatically converted in .pdf

Step by step instructions to reproduce the bug

Upload a .ai (Adobe illustrator file)
Download it = you get the file in .pdf

Can you replicate that error from the demo?

Yes

Observed behavior

FIle is converted from .ai to .pdf

Expected behavior

No conversion, uploaded .ai should stay .ai

[mickael-kerjean]

I can't replicate this issue on my end:

Do you have an environment for me where I can replicate this?