[hunsche]

Summary

Prevents progression_task from falsely marking open testcases as Fixed when a candidate build fails to start due to missing shared libraries or ABI symbol mismatches on the worker OS (e.g., during base OS migrations such as Ubuntu 24.04).

Details

• Adds _is_fatal_execution_or_linker_failure to detect:
  • POSIX loader/execve failure exit codes (126 and 127), and
  • Fatal dynamic linker diagnostics (error while loading shared libraries:, cannot open shared object file, and GLIBC_ / GLIBCXX_ / CXXABI_ version not found errors), even after reproduce_with_retries normalizes the final CrashResult.return_code to 0.
• Marks the revision's BuildData.is_bad_build = True and returns ErrorType.PROGRESSION_BAD_BUILD in both _testcase_reproduces_in_revision and _check_fixed_for_custom_binary instead of proceeding to _save_fixed_range.
• Adds unit test coverage in progression_task_test.py.