mkdir when destination directory doesn't exist

Fixes #8980

Make sure we mkdir if destination directory doesn't exist. I have no
idea why it doesn't work before

[ghstack-poisoned]

Author: larryliu0820

setup.py

@@ -463,8 +463,11 @@ def build_extension(self, ext: _BaseExtension) -> None:
         dst_file: Path = ext.dst_path(self)
 
         # Ensure that the destination directory exists.
-        self.mkpath(os.fspath(dst_file.parent))
-
+        if not dst_file.parent.exists():
+            print(f"DEBUG 1: dest parent directory {dst_file.parent}, exists? {dst_file.parent.exists()}")
+            self.mkpath(os.fspath(dst_file.parent))
+            print(f"DEBUG 2: dest parent directory {dst_file.parent}, exists? {dst_file.parent.exists()}")
+            
         # Copy the file.
         self.copy_file(os.fspath(src_file), os.fspath(dst_file))