Redmine

I had 3.0.3 running OK (Bitnami Windows download).
Tried to upgrade to 3.1.0.

Backed up 3.0.3 MySQL DB and restored it to 3.1.0.
Run rake db:migrate and got the following error.

F:\Bitnami\redmine-3.1.0-0\apps\redmine\htdocs>bundle exec rake db:migrate RAILS
_ENV=production --trace
DL is deprecated, please use Fiddle
** Invoke db:migrate (first_time)
** Invoke environment (first_time)
** Execute environment
** Invoke db:load_config (first_time)
** Execute db:load_config
** Execute db:migrate
== 20150528092912 CreateRolesManagedRoles: migrating ==========================
-- create_table(:roles_managed_roles, {:id=>false})
rake aborted!
StandardError: An error has occurred, all later migrations canceled:

Mysql2::Error: Table 'roles_managed_roles' already exists: CREATE TABLE `roles_m
anaged_roles` (`role_id` int(11) NOT NULL, `managed_role_id` int(11) NOT NULL) E
NGINE=InnoDBF:/Bitnami/redmine-3.1.0-0/apps/redmine/htdocs/vendor/bundle/ruby/2.
0.0/gems/activerecord-4.2.3/lib/active_record/connection_adapters/abstract_mysql
_adapter.rb:305:in `query'

Is it a bug in migration script or have I done something wrong?

Thanks in advance.