Great idea @patrick.bussmann! 
I think these #feature-request s should cover what you described, and both are planned for the near future:
- Bitrise API - abort build endpoint, in case you’d write a script or similar to auto abort
- A built in redundant build aborter feature, where you can configure which branches should have only one running build, aborting previous ones when a new build starts on the branch.
If there’s something not covered by these just let me know!