Revert "Fix #352 again (#357)"

This reverts commit 5fa27b5.

Author: bbatsov

copilot.el

@@ -989,8 +989,8 @@ provided."
                    (beginning-of-line)
                    (not (= (point) completion-start))))
         (setq start completion-start)
+        (setq end (- end (- (point) completion-start)))
         (delete-region completion-start (point)))
-      (setq start end)
       (copilot--async-request 'notifyAccepted (list :uuid uuid))
       (copilot-clear-overlay t)
       (if (derived-mode-p 'vterm-mode)