When trying to opening thread by passing non-opening post ID, find its proper

thread and show it instead of raising 404

boards/views/thread/thread.py

@@ -37,13 +37,13 b' class ThreadView(BaseBoardView, PostMixi'
 
     def get(self, request, post_id, form: PostForm=None):
         try:
-            opening_post = Post.objects.filter(id=post_id).first()
-        except IndexError:
+            opening_post = Post.objects.get(id=post_id)
+        except DoesNotExist:
             raise Http404
 
         # If this is not OP, don't show it as it is
-        if not opening_post or not opening_post.is_opening():
-            raise Http404
+        if not opening_post.is_opening():
+            return redirect(opening_post.get_thread().get_opening_post().get_url())
 
         if not form:
             form = PostForm(error_class=PlainErrorList)