I think their problem is that they need to keep old deploys alive for a long time because they have stateful long-running connections. So a blue/green deploy w

I think their problem is that they need to keep old deploys alive for a long time because they have stateful long-running connections. So a blue/green deploy wouldn't work because their blue deploy has to stay around for at least a month after green is deployed. There's no difference between the SHA and COLOR, I think the choice to use a git hash is because it's the logical choice (instead of randomly choosing a color from a list).