catchup rust-lang#126885

Signed-off-by: tison <wander4096@gmail.com>

Author: tisonkun

library/std/src/path.rs

@@ -1571,19 +1571,18 @@ impl PathBuf {
             Some(f) => f.as_encoded_bytes(),
         };
 
-        let new = extension.as_encoded_bytes();
+        let new = extension;
         if !new.is_empty() {
             // truncate until right after the file name
             // this is necessary for trimming the trailing slash
             let end_file_name = file_name[file_name.len()..].as_ptr().addr();
             let start = self.inner.as_encoded_bytes().as_ptr().addr();
-            let v = self.as_mut_vec();
-            v.truncate(end_file_name.wrapping_sub(start));
+            self.inner.truncate(end_file_name.wrapping_sub(start));
 
             // append the new extension
-            v.reserve_exact(new.len() + 1);
-            v.push(b'.');
-            v.extend_from_slice(new);
+            self.inner.reserve_exact(new.len() + 1);
+            self.inner.push(OsStr::new("."));
+            self.inner.push(new);
         }
 
         true