rushpy2 submission doesn't work with multiprocessing

[kc-chong]

When running rushpy2 submission using multiprocessing, I got sporadic issues, specifically with errornous reading of topology files.
I've uploaded my chelpG submission script with Manager.lock mechanism. But you can test it by removing the Manger.lock mechanism to replicate the error.

Sporadic error:

submit_chelpG.py

Expecting ',' delimiter: line 769 column 55 (char 32821)

[seankhl]

Multiprocessing shouldn't be necessary; jobs can be submitted and then collected later.

If a need for this can be exemplified, this issue can be re-opened.

[seankhl]

We may want to support this (for reasons related to principle of least surprise). At the very least should add an FAQ-like message explaining how submit+collect can effectively achieve the same thing.