The retrieval of the file path at a given revision from the restricted changeset href (`<rev>/<reponame>/<path>`) was broken, for several reasons:
- `<reponame>` was removed before the `<rev>` number was removed
- whenever `<path>` is empty, one should take the `original_path`
- unicode characters in `<path>` were encoded, need to do a `decodeURI` first
This should fix #9236.
