RFE: atomic operation for multiple component promotions

[javierpena]

When using components and trying to promote multiple commits at the same time, we have to iterate though all of them and call the /api/promote endpoint multiple times.

When this is done, we are creating a small window where a job could try to get the newly aggregated repo, and that would be quickly replaced by a new repo... So it will be hard to synchronize jobs and they may try to use different aggregates.

Ideally the DLRN api and dlrnapi client will support a batch operation where a user can send multiple commit and distro hash ids for a promotion and the updated repo and aggregated hash is ONLY written once. This would eliminate the issue.

[javierpena]

This was fixed with https://softwarefactory-project.io/r/17748