* Correction for a faulty condition
The current condition works for checking existence of the .sfs files on the local file system.
The proposed condition checks for the existence of the .sfs files on a remote server.
* Correction for NFS & NBD & HTTP boot
By default, Calamares searches for the .sfs files in the "bootmnt" directory.
When "copytoram==y" (relevant for NFS & NBD & HTTP boot), the .sfs files are stored in the "copytoram" directory.
The proposed code binds the "copytoram" dir with "bootmnt" so Calamares can "see" the .sfs. files.
Umount detaches the loop device automatically, but let's make it explicit to be sure. Additionally losetup gives: losetup: /dev/loop0: detach failed: No such device or address This is kind of expected, let's silent the error message.
