I tried also from a live session of Ubuntu 14.04.2 LTS booted from
ubuntu-14.04.2-desktop-amd64.iso
where I made the proposed repository available and installed usb-creator-gtk from it. 'Nothing else' was changed from the content of the iso file.
It still fails to install the bootloader and exits with the same message window (as when trying in the installed system),
"Failed to install the bootloader. [Quit]"
I tried also from a live session of Ubuntu 14.04.2 LTS booted from
ubuntu- 14.04.2- desktop- amd64.iso
where I made the proposed repository available and installed usb-creator-gtk from it. 'Nothing else' was changed from the content of the iso file.
It still fails to install the bootloader and exits with the same message window (as when trying in the installed system),
"Failed to install the bootloader.
[Quit]"