PelicanFS doesn't let you mount to subpaths in a federation

[jhiemstrawisc]

I was recently playing around with PelicanFS when I instantiated a PelicanFileSystem in a way that I expected to work:

>>> pelfs = PelicanFileSystem("pelican://osg-htc.org/ospool/ap40/justin.hiemstra")
>>> pelfs.ls("/")
DEBUG:fsspec.pelican:Ensuring that / is a pelican compatible path...
DEBUG:fsspec.pelican:Compatible path: /
DEBUG:fsspec.pelican:Finding the collections endpoint for /...
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/jhiemstra/.local/share/mamba/envs/test-pelicanfs/lib/python3.12/site-packages/fsspec/asyn.py", line 118, in wrapper
    return sync(self.loop, func, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/jhiemstra/.local/share/mamba/envs/test-pelicanfs/lib/python3.12/site-packages/fsspec/asyn.py", line 103, in sync
    raise return_result
  File "/home/jhiemstra/.local/share/mamba/envs/test-pelicanfs/lib/python3.12/site-packages/fsspec/asyn.py", line 56, in _runner
    result[0] = await coro
                ^^^^^^^^^^
  File "/home/jhiemstra/snakemake-executor-dev/pelicanfs/src/pelicanfs/core.py", line 704, in wrapper
    data_url, director_response = await self.get_dirlist_url(path)
                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/jhiemstra/snakemake-executor-dev/pelicanfs/src/pelicanfs/core.py", line 630, in get_dirlist_url
    raise BadDirectorResponse()
pelicanfs.exceptions.BadDirectorResponse

I think the issue is that a PelicanFileSystem expects only the pelican://osg-htc.org bit, not the additional path. However, it feels like I as a user should be able to instantiate the "filesystem" at a "sub directory" like I tried to do in this example, such that any pelfs.<operation>("/some/path") is relative to the path I provided when I set things up.

I'm not sure whether this is a feature request or a bug report because I don't know what was intended.