[todo] forge-insert-topic-state: Use forge-topic-unmerged face correctly

Use it for closed pull-requests that have been closed without merging.
That was always the intention.

lisp/forge-pullreq.el

@@ -267,7 +267,20 @@ Also see option `forge-topic-list-limit'."
                       (oref pullreq number))
               'font-lock-face (if (oref pullreq merged)
                                   'forge-topic-merged
-                                'forge-topic-unmerged)))
+                                'forge-topic-unmerged)
+              ;;'font-lock-face (forge--topic-face pullreq)
+              ))
+
+;; TODO we're gonna need more faces
+
+(defun forge--topic-face (topic)
+  (pcase-exhaustive (list (oref topic state)
+                          (forge-pullreq-p forge-buffer-topic))
+    (`(merged ,_)  'forge-topic-merged)
+    ('(closed nil) 'forge-topic-closed)
+    ('(closed t)   'forge-topic-unmerged)
+    (`(open   ,_)  'forge-topic-open))))))))
+
 
 (cl-defmethod forge--topic-type-prefix ((pullreq forge-pullreq))
   (if (forge--childp (forge-get-repository pullreq) 'forge-gitlab-repository)

lisp/forge-topic.el

@@ -131,7 +131,7 @@ implement such a function themselves.  See #447.")
   :group 'forge-faces)
 
 (defface forge-topic-unmerged
-  '((t :inherit magit-dimmed :slant italic))
+  '((t :inherit magit-dimmed :strike-through t))
   "Face used for number of unmerged pull-requests."
   :group 'forge-faces)
 
@@ -524,11 +524,7 @@ an error."
              (let ((state (oref topic state)))
                (magit--propertize-face
                 (symbol-name state)
-                (pcase (list state (forge-pullreq-p (forge-topic-at-point)))
-                  ('(merged) 'forge-topic-merged)
-                  ('(closed) 'forge-topic-closed)
-                  ('(open t) 'forge-topic-unmerged)
-                  ('(open)   'forge-topic-open))))))))
+                ))))))
 
 (defvar-keymap forge-topic-draft-section-map
   "<remap> <magit-edit-thing>" #'forge-edit-topic-draft)