Fix SearchEngine.search with limit

Author: danny0838

webscrapbook/scrapbook/search.py

@@ -522,14 +522,22 @@ def run(self):
     def search(self):
         results = self.search_books()
         limit = self.query.limit
+
         if limit >= 0:
             i = 0
             for item in results:
                 i += 1
                 if i > limit:
                     break
                 yield item
+
+            # In some Python implementation (e.g. PyPy with Python 3.11)
+            # returning from this function doesn't close results automatically,
+            # causing the acquired lock not released.
+            results.close()
+
             return
+
         yield from results
 
     def search_books(self):