Branch merging with gatekeeper and push on causes git failures with concurrent builds

[PeterL]

We have a plan setup to do CI - it monitors the master branch of a Git repository with branch merging enabled, using the gatekeeper strategy and we have multiple agents enabled so we can build multiple plans. This works fine when different plans are building, but bamboo will build multiple branches of a plan and invariably, one of them will not push to the remote because it is behind the tip due to the other. Bamboo should not build multiple branches that have push enabled.

[PeterL]

We just aren't doing this anymore, especially since we're using pull requests in Stash with the auto-merge from release branches down to newer versions. We do still let Bamboo build other branches, and we require that they have 1+ successful build before we allow the merge.

[ehummelPP]

Just wondering if anyone figured this scenario out? We hit it today and are wondering how to resolve this. Right now we allocated the entire plan to only use a single remote agent to force serialization, but that is sub-optimal in scenarios where the agent is offline, etc.