Comment 15 for bug 956481

The attached patch applied to /usr/lib/ubiquity/yaboot-installer/yaboot-installer on a live ISO allowed me install the bootloader to a USB partition successfully.

I'm not 100% sure I'm using the function map_of_path correctly in the patch. Other instances of that function seem more complicated.

yaboot-installer may fail in other ways so I think ubiquity still needs a way to deal with this cleanly.