[3.14] gh-154307: Fix TemporaryDirectory cleanup on DragonFly BSD (GH-154309) (GH-154312)

On DragonFly BSD, removing a file or directory with the UF_NOUNLINK flag
fails with EISDIR (IsADirectoryError) instead of EPERM, so the cleanup did
not reset the flags.  Handle IsADirectoryError the same as PermissionError.
(cherry picked from commit 1c1088b)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: 3 people

Lib/tempfile.py

@@ -915,7 +915,8 @@ def __init__(self, suffix=None, prefix=None, dir=None,
     @classmethod
     def _rmtree(cls, name, ignore_errors=False, repeated=False):
         def onexc(func, path, exc):
-            if isinstance(exc, PermissionError):
+            # On DragonFly BSD, UF_NOUNLINK removal fails with EISDIR, not EPERM.
+            if isinstance(exc, (PermissionError, IsADirectoryError)):
                 if repeated and path == name:
                     if ignore_errors:
                         return

Misc/NEWS.d/next/Library/2026-07-21-01-13-39.gh-issue-154307.UNFKL4.rst

@@ -0,0 +1,3 @@
+Fix :meth:`tempfile.TemporaryDirectory.cleanup` on DragonFly BSD, where removing
+a file with the ``UF_NOUNLINK`` flag failed with ``EISDIR`` instead of
+``EPERM``.