Code folding confused by edits

This happens not only for current master, but I just confirmed, that it is present there.
In the attachments you can see example code and my edits. Take a look at folding indicator in the firs and last picture. This is not only display error - it actually folds code like that. Basically when I flatten some nested blocks, I hit this error. And from now on I cannot fold normally. Instead it folds everything to the very end of edited file, which is quite annoying with longer source.

The only way I found to fix folding is to close and reopen the editor.