ecl-test failing if missing section in json

I have a custom ecl-test.json file to change some paths etc - with latest master system running ecl-test gave me an error:

[Error] RegressMain error:Error (6007): Regression Test Engine internal error
[Error]
[Error] Traceback (most recent call last):
File "/Users/rchapman/HPCC-Platform/testing/regress/hpcc/common/dict.py", line 27, in _getattr_
return self.__d[attr]
KeyError: 'setupExtraDParams'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "./ecl-test", line 407, in main
self.args.setupExtraD = self.config.setupExtraDParams
File "/Users/rchapman/HPCC-Platform/testing/regress/hpcc/common/dict.py", line 29, in _getattr_
raise AttributeError
AttributeError

I was able to "fix" by copying some info from the default ecl-test.json into my custom one, but really missing info should be handled more gracefully