intention, if the db query fails
* the `sort -u` was unnecessary anyways
* the `sort -u` swallowed the exit code of mysql_run_query
* failing mysql_run_query should stop the execution flow, i.e. not remove the intention
* Do not lock build list, so builders can get jobs.
* This may lead to builders getting for jobs, that are currently overwritten or deleted. This should not be worse than if the builder got the job before running get-package-updates, though.