[Development] Be careful with duplicate Change-Ids in multiple branches in gerrit

[Liang Qi]

This is a very common issue when I do the integraton work in qt5.

For example, currently we have 5.12->5.13->dev merge order, and the last round 5.13->5.13.0 today. One change(changeA) had been integrated in 5.13, and another change(changeB) with duplicate Change-Id was pushed to 5.13.0 branch with status:open. When I try to merge 5.13 to 5.13.0, the changeB will be picked up by gerrit and be part of the integration, which I found in COIN. Normally that integation will fail, but I am not 100% sure.

I only know the phenomenon, but not the root cause.

If you have a change was merged in lower branch, please try to avoid use duplicate Change-Id in upper branch, at least in the current merge order.

If you have a change landed in 5.12, and it's ok to have duplicate Change-Id when you cherry-picked it to 5.9, because we don't do merge from 5.9 to 5.12.

Best Regards,
Liang