concurrent submissions do not smartly iterate on id numbers

[mingness]

When there are two concurrent submissions, they will both be referenced to main, so will have the same id number. That means merges will have to be done one at a time, and after the first, the action for the subsequent submission should be rerun. Perhaps open issues with new-contribution should all rerun upon changes to main?

[Stefterv]

Are the id's still used anywhere within the pipeline?

[mingness]

I think the id's are only used by the current contribution manager. They are not used by the contribution pipeline.

[Stefterv]

Only reference to id's that I could find where here:
https:///processing/processing4/app/src/processing/app/contrib/LocalContribution.java#L66-L68

I had a quick check locally and they are all set to null