Remove read-only files upon cleanup (#2501)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

CONTRIBUTORS

@@ -107,6 +107,7 @@ Pierre-Jean Campigotto
 Pierre-Luc Tessier Gagné
 Prakhar Gurunani
 Rahul Bangar
+Robert Gomulka
 Ronald Evers
 Ronny Pfannschmidt
 Ryuichi Ohori

docs/changelog/2498.bugfix.rst

@@ -0,0 +1 @@
+Remove read-only files in ``ensure_empty_dir``.

src/tox/util/path.py

@@ -1,10 +1,26 @@
+import errno
+import os
 import shutil
+import stat
 
 from tox import reporter
 
 
 def ensure_empty_dir(path):
     if path.check():
         reporter.info("  removing {}".format(path))
-        shutil.rmtree(str(path), ignore_errors=True)
+        shutil.rmtree(str(path), onerror=_remove_readonly)
         path.ensure(dir=1)
+
+
+def _remove_readonly(func, path, exc_info):
+    """Clear the readonly bit and reattempt the removal."""
+    if isinstance(exc_info[1], OSError):
+        if exc_info[1].errno == errno.EACCES:
+            try:
+                os.chmod(path, stat.S_IWRITE)
+                func(path)
+            except Exception:
+                # when second attempt fails, ignore the problem
+                # to maintain some level of backward compatibility
+                pass

tests/integration/test_path_utils_removal.py

@@ -0,0 +1,19 @@
+import os
+from stat import S_IREAD
+
+from tox.util.path import ensure_empty_dir
+
+
+def test_remove_read_only(tmpdir):
+    nested_dir = tmpdir / "nested_dir"
+    nested_dir.mkdir()
+
+    # create read-only file
+    read_only_file = nested_dir / "tmpfile.txt"
+    with open(str(read_only_file), "w"):
+        pass
+    os.chmod(str(read_only_file), S_IREAD)
+
+    ensure_empty_dir(nested_dir)
+
+    assert not os.listdir(str(nested_dir))