Comment 38 for bug 1117292

Looks to me like this would be an issue caused by remaining files from other iso images when they are done using usb-creator.

If you're running into the server install failing with such errors as "busybox-initramfs" failing to install or other messages saying that "apt-install or in-target are already in use"; see if you have a stray "casper" directory on the USB drive used to do the install.

This would happen for people writing a desktop image to a USB drive, then writing a server image without formatting; the base installer will pick the squashfs file from casper/ first if it's there, which could make the installation fail.