[Bug 36106] Non-text files reported as "plain text document"

[lucia_engel]

Public bug report changed:
https://launchpad.net/malone/bugs/36106

Short description changed to:
    Confirmed real JPEG and PDF files detected as "plain text files".
    Not all files of those type are affected. Error seen in both
    nautilus and terminal.
Description changed to:
    I just downloaded a .rar archive with jpg files in it. When I tried
    to open them, an error message

    
    Cannot Open XX.jpg

    The filename "XX.jpg" indicates that this file is of type "JPEG image". The content of the file indicate that the file is of type "plain text document". If you open this file, the file might present a security risk to your system.
    Do not open the file unless you created the file yourself, or received the file from a trusted source. To open the file, rename the file to the correct extension for "plain text document", then open the file normally. Alternatively, use the Open With menu to choose a specific application for the file.

    
    pops up. I'm sure this isn't a plain text file because I can open them in WinXP like pictures just fine. I tried to use Open With and changing the extension, but it doesn't work. I saw this error for some pdf files I downloaded yesterday too. I thought it was only because they were corrupted and deleted them. Now I know this isn't isolated.

    I tried to use both nautilus and the terminal to open the file but
    they both cannot recognize the files.

    I've searched bugzilla and came up with three similar bugs. #35813,
    #6031, #23272 have the same error message, though two are claimed to
    be either external (Scribus) or solved (in Dapper).

    A picture of the bug can be seen here
    http://arvindn.livejournal.com/15761.html