This was caused by inconsistent escaping of the URL in the prefix
check, so check the URL links back to the correct host and scheme
instead of the prefix check.
The decoded path check will catch any URLs which are outside of the
root.
The purpose of this is to make it easier to maintain and eventually to
allow the rclone backends to be re-used in other projects without
having to use the rclone configuration system.
The new code layout is documented in CONTRIBUTING.
