Skip "root" dirs too (#479)

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### Pull Request Checklist:
- [ ] This PR addresses an already opened issue (for bug fixes /
features)
    - This PR fixes #xyz
- [ ] (If applicable) Documentation has been added / updated (for bug
fixes / features).
- [ ] (If applicable) Tests have been added.
- [ ] This PR does not seem to break the templates.
- [x] CHANGELOG.rst has been updated (with summary of main changes).
- [x] Link to issue (:issue:`number`) and pull request (:pull:`number`)
has been added.

### What kind of change does this PR introduce?

Small fix upon #478. Skips even if a directory to skip is one of the
entries in `directory` or a parent of one of the entries.
I implemented it because I misunderstood an error I was having, but
still, this could be used in the specific scenario where you are running
`parse_directory` through an incremental stack of xscen configurations.
To remove en entry of the `directories` list of a previous
configuration, you would only need to add a `skip_dirs` entry, and not
rewrite the filtered `directories`.

This also adds logging calls when skipping. And a precision to the doc
about the absoluteness of paths to skip.

### Does this PR introduce a breaking change?
No.

### Other information:

CHANGELOG.rst

@@ -10,7 +10,7 @@ New features and enhancements
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 * ``xs.io.make_toc`` now includes the global attributes of the dataset after the information about the variables. (:pull:`473`).
 * New function ``xs.get_warming_level_from_period`` to get the warming level associated with a given time horizon. (:pull:`474`).
-* Added ability to skip whole folders to ``xs.parse_directory`` with argument ``skip_dirs``.
+* Added ability to skip whole folders to ``xs.parse_directory`` with argument ``skip_dirs``. (:pull:`478`, :pull:`479`).
 
 Breaking changes
 ^^^^^^^^^^^^^^^^

src/xscen/catutils.py

@@ -148,10 +148,12 @@ def _find_assets(
         # Split zarr subdirectories from next iteration
         zarrs = []
         for dr in deepcopy(alldirs):
+            fdr = Path(top).joinpath(dr)
             if dr.endswith(".zarr"):
                 zarrs.append(dr)
                 alldirs.remove(dr)
-            if Path(top).joinpath(dr) in skip_dirs:
+            if fdr in skip_dirs:
+                logger.debug("Skipping %s", fdr)
                 alldirs.remove(dr)
 
         if (
@@ -323,6 +325,12 @@ def _parse_dir(  # noqa: C901
     exts = {Path(patt).suffix for patt in patterns}
     comp_patterns = list(map(_compile_pattern, patterns))
     checks = checks or []
+    parsed = []
+
+    root = Path(root)
+    if any([(skd in root.parents) or (skd == root) for skd in (skip_dirs or [])]):
+        logger.debug("Skipping %s", root)
+        return parsed
 
     # Multithread, communicating via FIFO queues.
     # This thread walks the directory
@@ -334,7 +342,6 @@ def _parse_dir(  # noqa: C901
     # Usually, the walking is the bottleneck.
     q_found = queue.Queue()
     q_checked = queue.Queue()
-    parsed = []
 
     def check_worker():
         # Worker that processes the checks.
@@ -517,7 +524,7 @@ def parse_directory(  # noqa: C901
         A glob pattern for path matching to accelerate the parsing of a directory tree if only a subtree is needed.
         Only folders matching the pattern are parsed to find datasets.
     skip_dirs : list of str or Paths, optional
-        A list of folders that will be removed from the search.
+        A list of folders that will be removed from the search, should be absolute.
     xr_open_kwargs: dict
         If needed, arguments to send xr.open_dataset() when opening the file to read the attributes.
     only_official_columns: bool