two jobs picked at the same time?
```
INFO: 2022-06-16 18:07:12,662 - datasets_server.worker - compute dataset 'classla/hr500k'
Downloading builder script: 100%|██████████| 13.4k/13.4k [00:00<00:00, 9.64MB/s]
started job DatasetJob[classla/hr500k] has a not the STARTED status (success). Force finishing anyway.
started job DatasetJob[classla/hr500k] has a non-empty finished_at field. Force finishing anyway.
CRITICAL: 2022-06-16 18:07:14,319 - datasets_server.worker - quit due to an uncaught error while processing the job: 2 or more items returned, instead of 1
Traceback (most recent call last):
  File "/src/services/worker/src/worker/main.py", line 200, in <module>
    loop()
  File "/src/services/worker/src/worker/main.py", line 185, in loop
    if has_resources() and process_next_job():
  File "/src/services/worker/src/worker/main.py", line 137, in process_next_job
    return process_next_dataset_job()
  File "/src/services/worker/src/worker/main.py", line 63, in process_next_dataset_job
    add_split_job(
  File "/src/services/worker/.venv/lib/python3.9/site-packages/libqueue/queue.py", line 193, in add_split_job
    add_job(
  File "/src/services/worker/.venv/lib/python3.9/site-packages/libqueue/queue.py", line 179, in add_job
    existing_jobs.filter(status__in=[Status.WAITING, Status.STARTED]).get()
  File "/src/services/worker/.venv/lib/python3.9/site-packages/mongoengine/queryset/base.py", line 281, in get
    raise queryset._document.MultipleObjectsReturned(
libqueue.queue.MultipleObjectsReturned: 2 or more items returned, instead of 1
make: *** [Makefile:19: run] Error 1
```
two jobs picked at the same time?: ```
INFO: 2022-06-16 18:07:12,662 - datasets_server.worker - compute dataset 'classla/hr500k'
Downloading builder script: 100%|██████████| 13.4k/13.4k [00:00<00:00, 9.64MB/s]
started job DatasetJob[classla/hr500k] has a not the STARTED status (success). Force finishing anyway.
started job DatasetJob[classla/hr500k] has a non-empty finished_at field. Force finishing anyway.
CRITICAL: 2022-06-16 18:07:14,319 - datasets_server.worker - quit due to an uncaught error while processing the job: 2 or more items returned, instead of 1
Traceback (most recent call last):
  File "/src/services/worker/src/worker/main.py", line 200, in <module>
    loop()
  File "/src/services/worker/src/worker/main.py", line 185, in loop
    if has_resources() and process_next_job():
  File "/src/services/worker/src/worker/main.py", line 137, in process_next_job
    return process_next_dataset_job()
  File "/src/services/worker/src/worker/main.py", line 63, in process_next_dataset_job
    add_split_job(
  File "/src/services/worker/.venv/lib/python3.9/site-packages/libqueue/queue.py", line 193, in add_split_job
    add_job(
  File "/src/services/worker/.venv/lib/python3.9/site-packages/libqueue/queue.py", line 179, in add_job
    existing_jobs.filter(status__in=[Status.WAITING, Status.STARTED]).get()
  File "/src/services/worker/.venv/lib/python3.9/site-packages/mongoengine/queryset/base.py", line 281, in get
    raise queryset._document.MultipleObjectsReturned(
libqueue.queue.MultipleObjectsReturned: 2 or more items returned, instead of 1
make: *** [Makefile:19: run] Error 1
```