By default, _redmine_session cookie path is /
This patch sets the path to ENV['RAILS_RELATIVE_URL_ROOT'], so that
multiple instances of redmine have distinct session cookies in any case.
diff --git a/lib/tasks/initializers.rake b/lib/tasks/initializers.rake
index ce87475..80c0268 100644
--- a/lib/tasks/initializers.rake
+++ b/lib/tasks/initializers.rake
@@ -15,8 +15,10 @@ file 'config/initializers/session_store.rb' do
 # change this key, all old sessions will become invalid! Make sure the
 # secret is at least 30 characters and all random, no regular words or
 # you'll be exposed to dictionary attacks.
+relativeUrlRoot = ENV['RAILS_RELATIVE_URL_ROOT']
 ActionController::Base.session = {
   :session_key => '_redmine_session',
+  :session_path => (relativeUrlRoot.nil? or relativeUrlRoot.empty?) ? '/' : relativeUrlRoot,
   :secret => '#{secret}'
 }
 EOF