fix(sphinx): recursive dir copy

[oxidase]

The fix prevents recursive directories copy if srcdir = pathlib.Path(args[1]) at https://github.com/bazel-contrib/rules_python/blob/278664d7/sphinxdocs/sphinxdocs/private/sphinx_build.py#L555 is '.'. which results to

   raise DirectorySyncerError(list(self._errors))
DirectorySyncerError: Encountered 1 error(s) during sync:
  - [Errno 36] File name too long: '.worker-in.d/.worker-in.d/.worker-in.d/.worker-in.d/<repeated many times>

[rickeylev]

How does . end up being passed as the source directory to copy?

[oxidase]

this is my local rule which uses sphinx and doxygen.

What it looks simplified like

    args = ctx.actions.args()  

    args.add(source_prefix) # here it can be "."
    args.add(output_dir.path)
    
    ctx.actions.run(
        executable = ctx.executable._sphinx,
        arguments = [args],
...

where ctx.executable._sphinx is sphinx_build_binary from @sphinxdocs//sphinxdocs:sphinx.bzl and the target is defined in the directory where conf.py is located.