The problem:
Changes to test processes in the code repo require changes to the build plan.
If your development lifecycle allows requires pull-requests and code reviews your changes will need to be tested before they can be merged into the mainstream.
However, to test the changes work correctly you may have to make changes to the build plans but doing this will affect the existing code and pull requests that are reliant on the original build plan.

The solution:
Enable the build plan to be configured from a file within the version control system (in a similar way to Travis).
This will allow developers and testers to make necessary changes to the test process without breaking the process before the changes has been accepted.