Refactor ostree-prepare-root: Perform chdir to deploy directory earlier
Refactor ostree-prepare-root: Perform chdir to deploy directory earlier

...for simplicity.  This way we don't need to keep concatenating
deploy_path to everything.  We can just refer relative to the current
working directory.

We need to do this after bind-mounting it over itself otherwise our cwd
is still on the non-bind-mounted filesystem below.

Closes: #403
Approved by: cgwalters

gatispaeglis/ostree,gatispaeglis/ostree,gatispaeglis/ostree,gatispaeglis/ostree,gatispaeglis/ostree,GNOME/ostree,GNOME/ostree,gatispaeglis/ostree,GNOME/ostree,GNOME/ostree,GNOME/ostree