(debug): Allow recursive minibuffers if we're in a minibuffer already.

lisp/emacs-lisp/debug.el

@@ -108,6 +108,9 @@ first will be printed into the backtrace buffer."
 	  last-event-frame
 	  overriding-local-map
 	  load-read-function
+	  ;; If we are inside a minibuffer, allow nesting
+	  ;; so that we don't get an error from the `e' command.
+	  (enable-recursive-minibuffers (> (minibuffer-depth) 0))
 	  (standard-input t) (standard-output t)
 	  (cursor-in-echo-area nil))
       (unwind-protect