Simplify temporary_directory and use safe_rmtree

poetry/core/utils/helpers.py

@@ -34,17 +34,9 @@ def normalize_version(version):  # type: (str) -> str
 
 @contextmanager
 def temporary_directory(*args, **kwargs):
-    try:
-        from tempfile import TemporaryDirectory
-
-        with TemporaryDirectory(*args, **kwargs) as name:
-            yield name
-    except ImportError:
-        name = tempfile.mkdtemp(*args, **kwargs)
-        try:
-            yield name
-        finally:
-            shutil.rmtree(name)
+    name = tempfile.mkdtemp(*args, **kwargs)
+    yield name
+    safe_rmtree(name)
 
 
 def parse_requires(requires):  # type: (str) -> List[str]

tests/utils/test_helpers.py

@@ -1,7 +1,12 @@
+import os
+
+from stat import S_IREAD
+
 import pytest
 
 from poetry.core.utils.helpers import canonicalize_name
 from poetry.core.utils.helpers import parse_requires
+from poetry.core.utils.helpers import temporary_directory
 
 
 def test_parse_requires():
@@ -62,3 +67,14 @@ def test_parse_requires():
 )
 def test_utils_helpers_canonical_names(raw):
     assert canonicalize_name(raw) == "a-b-c"
+
+
+def test_utils_helpers_temporary_directory_readonly_file():
+    with temporary_directory() as temp_dir:
+        readonly_filename = os.path.join(temp_dir, "file.txt")
+        with open(readonly_filename, "w+") as readonly_file:
+            readonly_file.write("Poetry rocks!")
+        os.chmod(str(readonly_filename), S_IREAD)
+
+    assert not os.path.exists(temp_dir)
+    assert not os.path.exists(readonly_filename)