Tests use PortAssignment#unique for assignment of the ports to bind during tests. Currently, this method works by using a monotonically increasing counter from a static starting point. Generally, this is sufficient to achieve uniqueness within a single JVM process, but it does not achieve uniqueness across multiple processes on the same host. This can cause tests to get bind errors if there are multiple pre-commit jobs running concurrently on the same Jenkins host. This also prevents running tests in parallel to improve the speed of pre-commit runs.