If you attempt a build and it fails for whatever reasons (say, a
configuration issue) and then you retry your build without calling
lh_clean, you can sometimes run into an issue with the
'deconfiguring file /bin/hostname' step. It'll try to move
chroot/bin/hostname.orig to chroot/bin/hostname but
chroot/bin/hostname.orig won't exist as chroot/bin/hostname hasn't
been moved aside like it expects (ie. the original file is still
chroot/bin/hostname). This is frustrating since if the error was
ignored, the build would be able to complete successfully and as
expected. So, let lh_chroot_hostname check if
'chroot/bin/hostname.orig' exists before attempting to
move it to 'chroot/bin/hostname'.