Add default tag instead of raising an error when no section is specified

boards/config/default_settings.ini

@@ -16,6 +16,7 b' PowDifficulty = 0'
 # Delay in seconds
 PostingDelay = 30
 Autoban = false
+DefaultTag = test
 
 [Messages]
 # Thread bumplimit

boards/forms.py

@@ -435,8 +435,11 b' class ThreadForm(PostForm):'
                 break
 
         if not required_tag_exists:
-            raise forms.ValidationError(
-                _('Need at least one section.'))
+            default_tag_name = board_settings.get('Forms', 'DefaultTag')\
+                    .strip().lower()
+            default_tag, created = Tag.objects.get_or_create(
+                    name=default_tag_name, required=True)
+            tag_set.add(default_tag)
 
         return tag_set