treat failure to remove temporary directory as a warning instead of a…

… failure

green/cmdline.py

@@ -81,14 +81,21 @@ def _main(argv, testing):
 def main(argv=None, testing=False):
     # create the temp dir only once (i.e., not while in the recursed call)
     if os.environ.get("TMPDIR") is None:  # pragma: nocover
-        with tempfile.TemporaryDirectory() as temp_dir_for_tests:
-            try:
-                os.environ["TMPDIR"] = temp_dir_for_tests
-                tempfile.tempdir = temp_dir_for_tests
-                return _main(argv, testing)
-            finally:
-                del os.environ["TMPDIR"]
-                tempfile.tempdir = None
+        try:
+            with tempfile.TemporaryDirectory() as temp_dir_for_tests:
+                try:
+                    os.environ["TMPDIR"] = temp_dir_for_tests
+                    tempfile.tempdir = temp_dir_for_tests
+                    return _main(argv, testing)
+                finally:
+                    del os.environ["TMPDIR"]
+                    tempfile.tempdir = None
+        except OSError as os_error:
+            if os_error.errno == 39:
+                # "Directory not empty" when trying to delete the temp dir can just be a warning
+                print("warning: {}".format(os_error.strerror))
+            else:
+                raise (os_error)
     else:
         return _main(argv, testing)