Bug in uploading an image file whose name contains a plus sign

Hello,

I just uploaded an image file whose name contains a plus sign (e.g. A + B.png). I tried to show it in my wiki but it failed. Then I tried to directly access the image by typing the url in my browser, and it showed me the log as follows:

Happstack 7.4.4

Something went wrong here
Internal server error
Everything has stopped

The error was "Could not getWikiBase: (path, uri) = ("A + B.png","/A B.png")"

I think this bug is caused by unhandled plus sign. But I am not sure where the bug comes from (Happstack itself or the gitit).

Please check this issue. Thank you.