docs(dataset_tools): trim filespec split comments to describe behavior only

Drop issue-tracker references, CI-contract narration, and "battle-tested"/
"error-prone" editorializing from the _file_object_path_split helper docstring,
the files-list promotion comment, and the port-colon parsing tests. Comments now
minimally describe existing behavior.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XeYa8sEdeLGa1VX2frvoNz

Author: Nick Manganelli

src/coffea/dataset_tools/filespec.py

@@ -20,15 +20,10 @@
 
 
 def _file_object_path_split(path: str) -> tuple[str, str | None]:
-    """Split a file path into ``(filename, object_path)``, delegating to uproot.
-
-    ROOT files may be specified as ``"filename:object_path"`` (e.g. ``"file.root:Events"``), but the
-    filename itself can be an XRootD URL containing colons (a port, as in
-    ``"root://host:1094//store/f.root"``). Reimplementing that parse is error-prone, so we reuse
-    uproot's splitter, which understands the ``root://`` scheme, ``//`` separators, ports, and
-    Windows drive letters. coffea intentionally tracks uproot closely; the import and the behaviour
-    we depend on are pinned by ``test_uproot_file_object_path_split_contract`` so an upstream move is
-    flagged in CI rather than silently mis-parsing URLs.
+    """Split ``"filename:object_path"`` into ``(filename, object_path)``.
+
+    Delegates to uproot's splitter, which handles XRootD URLs whose host carries a
+    port colon (e.g. ``"root://host:1094//store/f.root"``).
     """
     from uproot._util import file_object_path_split
 
@@ -497,10 +492,10 @@ def preprocess_data(cls, data: Any) -> Any:
             files = data.pop("files")
             # promote files list to dict if necessary
             if isinstance(files, list):
-                # If files is a list, convert it to a dict and let it pass through the rest of the promotion logic.
-                # Each entry may embed a ROOT object path as a trailing ":Tree" suffix, but the filename itself may
-                # be an XRootD URL that contains colons (e.g. a port, "root://host:1094//path/f.root"). Delegate to
-                # uproot's battle-tested URL/object-path splitter so we never split on the port colon.
+                # Convert the files list to a dict and let it pass through the rest of the promotion logic.
+                # Each entry may embed a ROOT object path as a trailing ":Tree" suffix; the filename itself may
+                # be an XRootD URL that contains a port colon (e.g. "root://host:1094//path/f.root"), so use
+                # uproot's splitter to separate filename from object path rather than splitting on the port colon.
                 files_list = files
                 files = {}
                 for f in files_list:

tests/test_dataset_tools_filespec.py

@@ -1204,8 +1204,7 @@ def test_legacy_form_to_compressed_form_migration(self):
             ("file.root:Dir/Tree", ("file.root", "Dir/Tree")),
             # XRootD URL without a port and no object path (the "//" guard case)
             ("root://host//path/f.root", ("root://host//path/f.root", None)),
-            # XRootD URL WITH a port and no object path (issue #1578: must not
-            # split at the ':1094' port colon)
+            # XRootD URL WITH a port and no object path (must not split at the ':1094' port colon)
             (
                 "root://host:1094//path/f.root",
                 ("root://host:1094//path/f.root", None),
@@ -1225,18 +1224,15 @@ def test_legacy_form_to_compressed_form_migration(self):
         ],
     )
     def test_file_object_path_split(self, path, expected):
-        """Regression for issue #1578: XRootD URLs with a port must not be split
-        at the port colon when separating filename from ROOT object path."""
+        """XRootD URLs with a port are not split at the port colon when separating
+        the filename from a ROOT object path."""
         from coffea.dataset_tools.filespec import _file_object_path_split
 
         assert _file_object_path_split(path) == expected
 
     def test_uproot_file_object_path_split_contract(self):
-        """Pin the uproot dependency ``_file_object_path_split`` delegates to.
-
-        coffea reuses uproot's splitter rather than reimplementing XRootD/object-path
-        parsing; there is no in-house fallback. If uproot moves or changes the helper,
-        this fails loudly in CI so we adapt here, instead of silently mis-parsing URLs.
+        """Pin the ``uproot._util.file_object_path_split`` behaviour that
+        ``_file_object_path_split`` delegates to, so a change in uproot surfaces here.
         """
         from uproot._util import file_object_path_split
 
@@ -1264,14 +1260,8 @@ def test_list_input_xrootd_url_with_port_and_object_path(self):
         assert spec.object_path == "Events"
 
     def test_list_input_xrootd_url_with_port_no_object_path(self):
-        """Regression for issue #1578: an XRootD URL with a port and NO object
-        path (here a remote parquet directory, which forbids an object_path) must
-        not be split at the port colon.
-
-        Before the fix, "root://host:1094//store/data/dir.parquet" was split into
-        filename "root://host" with object_path "1094//store/data/dir.parquet",
-        which then failed validation because parquet files forbid an object_path.
-        """
+        """An XRootD URL with a port and no object path (here a remote parquet
+        directory, which forbids an object_path) is not split at the port colon."""
         ds = DatasetSpec(
             files=["root://host.cern.ch:1094//store/data/dir.parquet"],
             metadata={},