Time between batch cancellation and next batch start

Support
#1

Hi, I've been experimenting with the service at app.bors.tech and was wondering about this.

Suppose I have two PRs A and B:

  1. I first add a bors r+ comment on A and bors creates a batch A' and starts it right away (the status changes to "Running" within a minute or so).
  2. Then I add a bors r+ comment on B and bors creates a batch B' and queues it (the status is "Waiting to run").
  3. Suppose A' gets cancelled somehow.
  4. After some amount of time, the status of B' is changed from "Waiting to run" to "Running".

My question is: what determines the time delay in step 4? If A is successfully merged by bors, then from what I can tell there is no delay before the status of B' is changed to "Running".