Migration issue with mysql2

I've created a pull request for this
issue https://github.com/theforeman/foreman/pull/93

RAILS_ENV=production bundle exec rake db:migrate

fails with :

<— snip -->

== CreateMessages: migrating

··· ================================================= -- create_table(:messages) -> 0.0024s -- add_index(:messages, :value) rake aborted! An error has occurred, all later migrations canceled:

Mysql2::Error: BLOB/TEXT column ‘value’ used in key specification without a
key length: CREATE INDEX index_messages_on_value ON messages (value)

Tasks: TOP => db:migrate
(See full trace by running task with --trace)

also fails on CreateSources:

== CreateSources: migrating

– create_table(:sources)
-> 0.0025s
– add_index(:sources, :value)
rake aborted!
An error has occurred, all later migrations canceled:

Mysql2::Error: BLOB/TEXT column ‘value’ used in key specification without a
key length: CREATE INDEX index_sources_on_value ON sources (value)

Tasks: TOP => db:migrate
(See full trace by running task with --trace)

sorry, correct pull request is https://github.com/theforeman/foreman/pull/94