Parallelization may have broken mongodb store operations

[oesteban]

What happened?

This commit cf6995e seems to have resulted in a dramatic change of the stats:

What command did you use?

n/a

What version of the software are you running?

latest

How are you running this software?

Docker

Is your data BIDS valid?

Yes

Are you reusing any previously computed results?

No

Please copy and paste any relevant log output.

Additional information / screenshots

No response

[oesteban]

@mgxd I broke the retrieval script, can you review the commit and help me spot what I did wrong?