you have chosen to open 37910 which is a BIN file

I visited https://beta.launchpad.net/ubuntu/+source/gnome-volume-manager with a somewhat old feisty firefox and clicked on the link to +filebug. I then filled in some details (the title "usb stick not mounted") and from the list of bugs I opened various of them.

For one of them, I got a curious dialogue:
   Opening 37910
   You have chosen to open
     [picture of a sheet of paper] 37910
        which is a: BIN file
        from: https://beta.launchpad.net
   Would you like to save this file ? X Cancel [ <-' Save File ]

This is the second time this has happened to me; the first time was a result of typing launchpad.net/bugs/<some bug number> directly into the URL field.