Docker Support

Halting migrations due to a migration failure.

Destination path '/var/lib/pulp/published/docker/v1/export' already exists
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/pulp/server/db/manage.py", line 125, in main
    return _auto_manage_db(options)
  File "/usr/lib/python2.7/site-packages/pulp/server/db/manage.py", line 185, in _auto_manage_db
    migrate_database(options)
  File "/usr/lib/python2.7/site-packages/pulp/server/db/manage.py", line 98, in migrate_database
    update_current_version=not options.test)
  File "/usr/lib/python2.7/site-packages/pulp/server/db/migrate/models.py", line 161, in apply_migration
    migration.migrate()
  File "/usr/lib/python2.7/site-packages/pulp_docker/plugins/migrations/0001_v2_support.py", line 27, in migrate
    shutil.move(folder, NEW_DOCKER_V1_PUBLISH_PATH)
  File "/usr/lib64/python2.7/shutil.py", line 291, in move
    raise Error, "Destination path '%s' already exists" % real_dst
Error: Destination path '/var/lib/pulp/published/docker/v1/export' already exists

I would expect some if os.path.exists before the actual move. That could make migration to be runable more than once.