Steps to reproduce:

 * Running ikiwiki version 3.20130904.1ubuntu1 on Ubuntu 14.04 LTS
 * Also installed `perlmagick` and `libxml-writer-perl`
 * Enable attachment plugin
 * Set attachment rule to `mimetype(image/*)`
 * Attempt to attach an image (e.g. downloaded version of https://commons.wikimedia.org/wiki/Category:Lolcats#/media/File:You_gotz_a_lolcat.jpg )

What should happen:

 * Attachment is uploaded

What happens instead:

 * Error message: `prohibited by allowed_attachments (file MIME type is application/octet-stream, not image/*)`

Workaround:

 * Change attachment rule to `mimetype(image/*) or application/octet-stream`

Other notes:

 * Downloading and uploading from a Windows machine via Firefox

---

> File type detection relies on some of the external packages in ikiwiki's Suggests list.
>
> Do you have [[!ubupkg file]] installed?
>
> Do you have [[!ubupkg libfile-mimeinfo-perl]] installed?
>
> --[[smcv]]