Indeed, the problem goes away with emacs -Q. I investigated
further and found that the culprit is display-buffer-function being set
to popwin:display-buffer. Thus, I can load my current config and
evaluate (setq display-buffer-function nil). The problem will disappear.
still think that my patch is the right solution. The current code
expects display-buffer to behave in a certain way and Emacs gives us a
ton of ways to change that. Thus, we either need to explicitly set the
current buffer, or we can do away with trying to make *Occur* read-only.
And really, who needs that? Even if we don't set buffer-read-only, the
buffer has no self-insert-command bindings, and if you try to C-k the
header, it will still say "Text is read-only: #<buffer *Occur*>"
because there is a read-only text-property. And why shouldn't you delete
Thus, as far as I can tell, my change makes
the code more robust (no longer depending on display-buffer to work in a
particular way) and it has practically no drawbacks.