Multiple deploy hook calls do not immediately cancel builds

[jessetan]

Page to Investigate

https://vercel.com/docs/concepts/deployments/deploy-hooks#other-optimizations

Steps to Reproduce

According to the docs at https://vercel.com/docs/concepts/deployments/deploy-hooks#other-optimizations, calling the same deploy hook multiple times should only trigger a single build and all others are cancelled.
What I'm seeing is slightly different (deploy hooks are called from Sanity in our case):

1. Call deploy hook
2. Job A is created and starts building
3. Call deploy hook second time
4. Job B is created and remains queued
5. Call deploy hook a third time
6. Job C is created and remains queued:
   
7. Job A finishes building
8. Job C starts building, job B remain queued:
   
9. Job C finishes building, job B is cancelled:
   

Expected:
4. Job B is created and starts building, job A is cancelled mid-build and removed
6. Job C is created and starts building, job A & B are cancelled and removed

I understand that cancelling many builds may trigger some warning, but the current method will make job C wait unnecessarily for job A. It will also show job B as being queued while it will never be built.
If someone is calling the deploy hook a lot, this can mean many queued jobs in the overview that will never be built.