How to pass command-line arg to docker build image invocation?

[nathan lord]

How can we pass a command-line arg (e.g. --cap-add SYS_PTRACE) to the docker invocation when Bitbucket Pipelines launches a docker build environment?

It's necessary to resolve the exact issue here:
https://community.atlassian.com/t5/Bitbucket-Pipelines-questions/What-docker-version-is-Bitbucket-Pipelines-running/qaq-p/1227081

I haven't been able to find any documentation or example anywhere that illustrates how to make this work.

[Michael March]

Atlassian, still, is very restrictive on what options can be set when evoking the root Docker environment(s).