First, downgrade your version of Buildbot:

pip install buildbot==0.8.3p1

If you run buildbot now, you'll see:

        buildbot.db.exceptions.DatabaseNotReadyError: 
        The Buildmaster database needs to be upgraded before this version of buildbot
        can run.  Use the following command-line
            buildbot upgrade-master path/to/master
        to upgrade the database, and try starting the buildmaster again.  You may want
        to make a backup of your buildmaster before doing so.  If you are using MySQL,
        you must specify the connector string on the upgrade-master command line:
            buildbot upgrade-master --db=<db-connector-string> path/to/master

so adjust the version number downward:

$ sqlite3 state.db
SQLite version 3.7.5
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> create table version ( version integer );
sqlite> insert into version values (6);
sqlite> drop table migrate_version;