Comment 1 for bug 1177667

This problem is caused because the' SHA256SUMS' file downloaded now includes the hash for saucy, therefore those images must exist as well... The following patch fix the issue although it still uses the raring images. If you don't want to patch ubuntu-nexus7-installer the files can be download them manually in:

$XDG_DOWNLOAD_DIR/UbuntuNexus7

Example:

$ cd $XDG_DOWNLOAD_DIR/UbuntuNexus7
$ wget http://cdimage.ubuntu.com/daily-preinstalled/current/saucy-preinstalled-desktop-armhf+nexus7.bootimg
$ wget http://cdimage.ubuntu.com/daily-preinstalled/current/saucy-preinstalled-desktop-armhf+nexus7.img.gz

After that re running:

$ ubuntu-nexus7-installer

Should give no problems