When using a deployment strategy with an user input option older builds are cancelled as soon as the user acknowledges the input. That's working pretty well, however:
Frequent commits will clock up the executors all waiting on the same input if the user does not acknowledge 'quick' enough. We might be able to optimise this and free executors by automatically aborting old builds which are all sitting in the same milestone.

build #1

• milestone 1
• input
  -milestone 2

build #2 (newer commit)

• milestone 1
• input
• milestone 2

When build #2 reaches the input it's effectively in milestone 1, where #1 is currently sitting as well. It could be very good if at this point we would be able to abort #1 as we have a new build in the same milestone.

I was not able to find a solution achieving above behaviour, but if that's otherwise possible, I would be very happy to implement it, although I believe it would be a good addition to excellent milestone pattern readily available.