forge-read-topic-lift-limit: Refresh completions for built-in completion

Without this, the list of displayed choices is not updated until the
user invokes `minibuffer-complete'.  With this, the up-to-date list
of available choices is displayed, even if previously it was not
displayed.  There probably is a way to just update the list, iff it
is already displayed, but I cannot find it.

Author: tarsius

lisp/forge-topic.el

@@ -774,11 +774,14 @@ can be selected from the start."
              forge-limit-topic-choices)
     (setq-local forge-limit-topic-choices nil)
     (forge-read-topic--remove-prompt-hint)
-    (when (and (bound-and-true-p vertico-mode)
-               (boundp 'vertico--input)
-               (fboundp 'vertico--exhibit))
-      (setq vertico--input t)
-      (vertico--exhibit))))
+    (cond
+      ((and (bound-and-true-p vertico-mode)
+            (boundp 'vertico--input)
+            (fboundp 'vertico--exhibit))
+       (setq vertico--input t)
+       (vertico--exhibit))
+      ((minibuffer-completion-help (minibuffer--completion-prompt-end)
+                                   (point-max))))))
 
 (defun forge-read-topic--remove-prompt-hint ()
   (when (minibufferp)