merge upstream changes (1f45cd3 - pull request #5).

awesome nested set was deleted, so we take only half of the changes

app/models/issue.rb

@@ -109,6 +109,26 @@ class Issue < ActiveRecord::Base
     }
   }
 
+  # find all issues
+  # * having set a parent_id where the root_id
+  #   1) points to self
+  #   2) points to an issue with a parent
+  #   3) points to an issue having a different root_id
+  # * having not set a parent_id but a root_id
+  # This unfortunately does not find the issue with the id 3 in the following example
+  # | id  | parent_id | root_id |
+  # | 1   |           | 1       |
+  # | 2   | 1         | 2       |
+  # | 3   | 2         | 2       |
+  # This would only be possible using recursive statements
+  named_scope :invalid_root_ids, { :conditions => "(issues.parent_id IS NOT NULL AND " +
+                                                    "(issues.root_id = issues.id OR " +
+                                                    "(issues.root_id = parent_issues.id AND parent_issues.parent_id IS NOT NULL) OR " +
+                                                    "(issues.root_id != parent_issues.root_id))" +
+                                                  ") OR " +
+                                                  "(issues.parent_id IS NULL AND issues.root_id != issues.id)",
+                                   :joins => "LEFT OUTER JOIN issues parent_issues ON parent_issues.id = issues.parent_id" }
+
   before_create :default_assign
   before_save :close_duplicates, :update_done_ratio_from_issue_status
   after_save :reschedule_following_issues, :update_nested_set_attributes, :update_parent_attributes
@@ -772,6 +792,59 @@ class Issue < ActiveRecord::Base
     projects
   end
 
+  # method from acts_as_nested_set
+  def self.valid?
+    super && invalid_root_ids.empty?
+  end
+
+  def self.all_invalid
+    (super + invalid_root_ids).uniq
+  end
+
+  def self.rebuild_silently!(roots = nil)
+
+    invalid_root_ids_to_fix = if roots.is_a? Array
+                                roots
+                              elsif roots.present?
+                                [roots]
+                              else
+                                []
+                              end
+
+    known_issue_parents = Hash.new do |hash, ancestor_id|
+      hash[ancestor_id] = Issue.find_by_id(ancestor_id)
+    end
+
+    fix_known_invalid_root_ids = lambda do
+      issues = invalid_root_ids
+
+      issues_roots = []
+
+      issues.each do |issue|
+        # At this point we can not trust nested set methods as the root_id is invalid.
+        # Therefore we trust the parent_issue_id to fetch all ancestors until we find the root
+        ancestor = issue
+
+        while ancestor.parent_issue_id do
+          ancestor = known_issue_parents[ancestor.parent_issue_id]
+        end
+
+        issues_roots << ancestor
+
+        if invalid_root_ids_to_fix.empty? || invalid_root_ids_to_fix.map(&:id).include?(ancestor.id)
+          Issue.update_all({ :root_id => ancestor.id },
+                           { :id => issue.id })
+        end
+      end
+
+      fix_known_invalid_root_ids.call unless (issues_roots.map(&:id) & invalid_root_ids_to_fix.map(&:id)).empty?
+    end
+
+    fix_known_invalid_root_ids.call
+
+    super
+  end
+
   private
 
   def update_nested_set_attributes