Incorrect formatting of plain text files

[zenhack]

If I have a plaintext file (.txt extension) in a davros folder, the "preview" seems to render it as html, which has the effect of destroying all formatting, plus using a variable width-font, which depending on the content can be not what you want. Contrast this with how browsers display things flagged as text/plain, e.g:

https://github.com/robots.txt