I do it to get project name

you can still get it from the task object (even after closing it)

another place I was using was to see if i am in a pipeline task

Yes that makes sense, this is one of the use cases (to see get access to the Task that is currently running). The bug itself will only happen after closing the Task (it needs to clear OS variable).
You can either upgrade to the 1.0.6rc2 or you can hack/fix it with :
os.environ.pop('CLEARML_PROC_MASTER_ID', None) os.environ.pop('TRAINS_PROC_MASTER_ID', None)