Fix off by one in undo stack size check

lkollar · lkollar · commit d7311af7ad8a · 2025-12-01T22:18:40.000Z
diff --git a/Lib/_pyrepl/reader.py b/Lib/_pyrepl/reader.py
@@ -901,7 +901,7 @@ def enter_insert_mode(self) -> None:
 
         self.vi_mode = VI_MODE_INSERT
 
-        if len(self.undo_stack) > MAX_VI_UNDO_STACK_SIZE:
+        if len(self.undo_stack) >= MAX_VI_UNDO_STACK_SIZE:
             self.undo_stack.pop(0)
 
         self.undo_stack.append(ViUndoState(
