Possible bug in process cancellation on timeout

[petertrr]

In the test execute warn plugin with timeout()[jvm]: org.opentest4j.AssertionFailedError: expected: <Fail(reason=ProcessTimeoutException: Timeout is reached, shortReason=ProcessTimeoutException: Timeout is reached)> but was: <Fail(reason=ProcessExecutionException: Stream closed, shortReason=ProcessExecutionException: Stream closed)>. This error occurs very rarely (but in #310 I've seen it twice already, both on MacOS, but it could be just a coincidence), but must indicate some flaw in process destruction/cancellation logic. For example, process is destroyed from another thread, while we are already reading its output.