Update Post.get_absolute_url() to always include the post ID

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

board/models.py

@@ -173,15 +173,11 @@ class Post(models.Model):
         thumb_temp.close()
 
     def get_absolute_url(self):
-        if self.op is None:
-            return reverse(
-                "board:post_detail", kwargs={"url": self.board.url, "id": self.id}
-            )
-        else:
+        op = self.op if self.op else self
         return (
             reverse(
                 "board:post_detail",
-                    kwargs={"url": self.board.url, "id": self.op.id},
+                kwargs={"url": self.board.url, "id": op.id},
             )
             + f"#p{self.id}"
         )