Document characters being stripped from labels

db/migrate/20140729152420_migrate_taggable_labels.rb

@@ -15,7 +15,9 @@ class MigrateTaggableLabels < ActiveRecord::Migration
 
   def create_label_from_tagging(tagging)
     target = tagging.taggable
-    label_name = tagging.tag.name.tr('?&,', '')
+    label_name = tagging.tag.name
+    # '?', '&' and ',' are no longer allowed in label names so we remove them
+    label_name.tr!('?&,', '')
     label = target.project.labels.find_or_create_by(title: label_name, color: Label::DEFAULT_COLOR)
 
     if label.valid? && LabelLink.create(label: label, target: target)

doc/update/6.0-to-7.2.md

@@ -6,6 +6,13 @@
 
 As of 6.1 issue numbers are project specific. This means all issues are renumbered and get a new number in their URL. If you use an old issue number URL and the issue number does not exist yet you are redirected to the new one. This conversion does not trigger if the old number already exists for this project, this is unlikely but will happen with old issues and large projects.
 
+## Editable labels
+
+In GitLab 7.2 we replace Issue and Merge Request tags with labels, making it
+possible to edit the label text and color. The characters '?', '&' and ',' are
+no longer allowed however so those will be removed from your tags during the
+database migrations for GitLab 7.2.
+
 ## 0. Backup
 
 It's useful to make a backup just in case things go south:

doc/update/7.1-to-7.2.md

 # From 7.1 to 7.2
 
+## Editable labels
+
+In GitLab 7.2 we replace Issue and Merge Request tags with labels, making it
+possible to edit the label text and color. The characters '?', '&' and ',' are
+no longer allowed however so those will be removed from your tags during the
+database migrations for GitLab 7.2.
+
 ### 0. Backup
 
 ```bash