improve exception_handling.
- any exception within a subthread is passed to main process
- replace ConnectionError with ConnectionException -> ConnecionError is used for filehandling and misplaced as general exception for master connections problems
Dear CI users! Due issues with our instance runner cluster on Kubernetes, we can currently offer only 1 instance runner. For fairness, we have to limit the runtime of CI jobs to 10 minutes. If you need more, please set up your own runner.