By: Tom Sydney Kerckhove <syd@cs-syd.eu>
Abort mutation run when coverage baseline tests fail When a coverage child observes a test failure during baseline collection, mutation testing against that suite would produce meaningless scores — the test was already red before any mutation ran. The coverage child now prints the offending test's output and a loud warning whenever a baseline test fails. Under --mutation-fail-fast it additionally exits with code 2; the parent treats that as a non-retryable abort signal, cancels the remaining workers via a new CoverageFailFast exception (distinct from the existing MutationFailFast used for survivors and uncovered mutations), and exits non-zero. The fail-fast value is forwarded to coverage children explicitly so the child's behaviour follows the parent's setting rather than its own default.