With -a, the jump to mount_it_now can skip the initialization of f, and

With -a, the jump to mount_it_now can skip the initialization of f, and
if we don't zero it after closing it we re-close a filehandle that isn't
open, and since this is a file _pointer_ it segfaults on a double free.

Yeah, subtle bug.  I need to break this out into separate functions if I can
figure out how to avoid making the code larger while doing so.  Part of
the general -a and -o remount work I need to do, but that's after 1.1.0...