Fix open_mfdataset for list of fsspec files (#9785)

* Fix open_mfdataset for list of fsspec files

* Rewrite to for loop

* Fixup

Author: phofl

xarray/backends/common.py

@@ -136,14 +136,15 @@ def _find_absolute_paths(
     def _normalize_path_list(
         lpaths: NestedSequence[str | os.PathLike],
     ) -> NestedSequence[str]:
-        return [
-            (
-                _normalize_path(p)
-                if isinstance(p, str | os.PathLike)
-                else _normalize_path_list(p)
-            )
-            for p in lpaths
-        ]
+        paths = []
+        for p in lpaths:
+            if isinstance(p, str | os.PathLike):
+                paths.append(_normalize_path(p))
+            elif isinstance(p, list):
+                paths.append(_normalize_path_list(p))  # type: ignore[arg-type]
+            else:
+                paths.append(p)  # type: ignore[arg-type]
+        return paths
 
     return _normalize_path_list(paths)
 

xarray/tests/test_backends.py

@@ -5511,6 +5511,8 @@ def test_source_encoding_always_present_with_fsspec() -> None:
         fs = fsspec.filesystem("file")
         with fs.open(tmp) as f, open_dataset(f) as ds:
             assert ds.encoding["source"] == tmp
+        with fs.open(tmp) as f, open_mfdataset([f]) as ds:
+            assert "foo" in ds
 
 
 def _assert_no_dates_out_of_range_warning(record):