Migrate to timestamp fails if group has no applied migrations

[BRMatt]

<zombor> bash minion db:migrate --group=profilereview --migrate-to=20110616111554
<zombor> --migrate-up works though
<BRMatt> What's the difference between the current timestamp and the target one?
<BRMatt> as in, how many migrations 
<zombor> there's only one migration in this case
<zombor> ErrorException [ 8 ]: Undefined index:  profilereview ~ /mnt/hgfs/sittercity/minion-migrations/classes/model/minion/migration.php [ 345 ]

https://github.com/kohana-minion/tasks-migrations/blob/develop/classes/model/minion/migration.php#L345