Add is duplicate to User admin

scipost/admin.py

@@ -41,9 +41,14 @@ class UserAdmin(UserAdmin):
         ContactToUserInline,
         ProductionUserInline
         ]
-    list_display = ['username', 'email', 'first_name', 'last_name', 'is_active', 'is_staff']
+    list_display = ['username', 'email', 'first_name', 'last_name',
+                    'is_active', 'is_staff', 'is_duplicate']
     search_fields = ['last_name', 'email']
 
+    def is_duplicate(self, obj):
+        return obj.contributor.is_duplicate
+    is_duplicate.short_description = 'Is duplicate?'
+    is_duplicate.boolean = True
 
 admin.site.unregister(User)
 admin.site.register(Contributor, ContributorAdmin)

scipost/models.py

@@ -93,6 +93,10 @@ class Contributor(models.Model):
         """
         return self.user.is_active and self.status == NORMAL_CONTRIBUTOR
 
+    @property
+    def is_duplicate(self):
+        return self.duplicate_of is not None
+
     @property
     def is_currently_available(self):
         """Check if Contributor is currently not marked as unavailable."""