Howto use CUSTOM_ENV_FARGATE_TASK_DEFINITION

Hi,

I have tried to use CUSTOM_ENV_FARGATE_TASK_DEFINITION in my gitlab-ci.yaml for setting a new TaskDefinition but it seems that this does not have any effect during execution. The fargate driver uses the task definition from fargate.toml. Is there any further documentation howto use CUSTOM_ENV_FARGATE_TASK_DEFINITION ?

We are using the latest runner and fargate driver:

Running with gitlab-runner 13.2.2 (a998cacd)
  on fargate-xxx WGJkJQsh
Preparing the "custom" executor
00:58
INFO[2020-08-06T14:58:39Z] Starting fargate                              PID=10702 version="0.2.0 (933d940)"
Edited by Philipp
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information