Fixing an incorrectly redirected newline.

Fixing an incorrectly redirected newline.

Since this newline was written to stdout it both messed up the the
display of errors while entering a LUKS passphrase, and caused
find_cow_device to return a bad string under certain
circumstances. Example: You have home-rw on /dev/sdX1. You'll first
be asked for passphrase for "live-rw on /dev/sdX1", which you skip (a
newline has been written to stdout now). Then you're asked for
"home-rw on /dev/sdX1", which is what you want so you enter it.
Thanks to the spurious newline find_cow_device returns "\n/dev/loopY",
which breaks some tests later.