path: introduce a `get_unique_pull_path_obj` function
Unlike the previous one, `get_unique_pull_path`, this function return the `path`
object, opening more option for the caller.
note that this highlight we don't actually need the `repo` argument to
`get_pull_paths`, however changing the API would be annoying for third party
extensions.
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public attribute not declared in interfaces: badpeer.badmethod