FIX: refreshing auto groups when min_username_length is long

app/models/group.rb

@@ -599,7 +599,15 @@ class Group < ActiveRecord::Base
   protected
 
   def name_format_validator
-    self.name.strip!
+
+    return if !name_changed?
+
+    # avoid strip! here, it works now
+    # but may not continue to work long term, especially
+    # once we start returning frozen strings
+    if self.name != (stripped = self.name.strip)
+      self.name = stripped
+    end
 
     UsernameValidator.perform_validation(self, 'name') || begin
       name_lower = self.name.downcase

spec/models/group_spec.rb

@@ -315,7 +315,7 @@ describe Group do
         default_locale = SiteSetting.default_locale
         I18n.locale = SiteSetting.default_locale = 'de'
 
-        another_group = Fabricate(:group,
+        _another_group = Fabricate(:group,
           name: I18n.t('groups.default_names.staff').upcase
         )
 
@@ -380,6 +380,17 @@ describe Group do
     admin.revoke_moderation!
     expect(real_admins).to be_empty
     expect(real_staff).to eq []
+
+    # we need some ninja work to set min username to 6
+
+    User.where('length(username) < 6').each do |u|
+      u.username = u.username + "ZZZZZZ"
+      u.save!
+    end
+
+    SiteSetting.min_username_length = 6
+    Group.refresh_automatic_groups!(:staff)
+    # should not explode here
   end
 
   it "Correctly updates automatic trust level groups" do