Revert "Remove attempted free uncommited in restore_savepoint"

This reverts commit a41f3ff.

Actually this optimization is useful because we allow restoring into
dirty transcations. The original commit message was wrong about that

src/transactions.rs

@@ -737,7 +737,11 @@ impl WriteTransaction {
             if whitelist.contains(&page) {
                 continue;
             }
-            freed_pages.push(page);
+            if self.mem.uncommitted(page) {
+                self.mem.free(page);
+            } else {
+                freed_pages.push(page);
+            }
         }
         *self.freed_pages.lock().unwrap() = freed_pages;
         self.tables.lock().unwrap().table_tree = TableTreeMut::new(
@@ -777,8 +781,12 @@ impl WriteTransaction {
                     && !freed_pages_hash.contains(&page)
                     && !whitelist.contains(&page)
                 {
-                    freed_pages.push(page);
-                    freed_pages_hash.insert(page);
+                    if self.mem.uncommitted(page) {
+                        self.mem.free(page);
+                    } else {
+                        freed_pages.push(page);
+                        freed_pages_hash.insert(page);
+                    }
                 }
             }
         }