drush_backend_batch_process doesn't support class static method for "finished"

[miteshmap]

If you try to run a batch with drush_backend_batch_process(), using already existing static methods of a class, It does work for "operations", But it doesn't work for "finished".

It should have work without any issue But as it's called like:
$batch_set['finished']($batch_set['success'], $batch_set['results'], $operations, $elapsed), Instead it should have called usingcall_user_func_array

[weitzman]

Merged both PRs. Thanks.

[miteshmap]

👍 thanks @weitzman, That was real quick 💯