forgot to add mem::forget() on key

Author: asder8215

library/alloc/src/collections/btree/map.rs

@@ -1328,7 +1328,7 @@ impl<K, V, A: Allocator + Clone> BTreeMap<K, V, A> {
                 }
             }
         } else {
-            // SAFETY: if we reach here, that means our cursor has reached
+            // Safety: if we reach here, that means our cursor has reached
             // the end of self BTreeMap, (other_key is greater than all the
             // previous self BTreeMap keys) so we just insert other_key here
             // at the end of the CursorMut
@@ -3488,9 +3488,10 @@ impl<'a, K: Ord, V, A: Allocator + Clone> CursorMutKey<'a, K, V, A> {
 
         let mut emptied_internal_root = false;
         if let Ok(next_kv) = current.next_kv() {
-            let ((_, val), pos) =
+            let ((key, val), pos) =
                 next_kv.remove_kv_tracking(|| emptied_internal_root = true, self.alloc.clone());
-            // Don't run destructor on next element's value
+            // Don't run destructor on next element's key and value
+            mem::forget(key);
             mem::forget(val);
             self.current = Some(pos);
             *self.length -= 1;