I think recent changes to validate bisect config broke, bisect jobs.
https://build.chromium.org/p/tryserver.chromium.perf/builders/win_fyi_perf_bisect


Traceback (most recent call last):
  File "E:\b\build\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\run.py", line 397, in run
    recipe_result = recipe_script.run(api, api._engine.properties)
  File "E:\b\build\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\loader.py", line 57, in run
    self.RunSteps, properties, self.PROPERTIES, api=api)
  File "E:\b\build\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\loader.py", line 512, in invoke_with_properties
    **additional_args)
  File "E:\b\build\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\loader.py", line 473, in _invoke_with_properties
    return callable_obj(*props, **additional_args)
  File "E:\b\build\scripts/slave\recipes\bisection/desktop_bisect.py", line 30, in RunSteps
    api.auto_bisect.start_try_job(api, update_step=update_step, bot_db=bot_db)
  File "E:\b\build\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\recipe_api.py", line 220, in _inner
    return func(*a, **kw)
  File "E:\b\build\scripts/slave\recipe_modules\auto_bisect\api.py", line 275, in start_try_job
    local_bisect.perform_bisect(self)  # pragma: no cover
  File "E:\b\build\scripts/slave\recipe_modules\auto_bisect\local_bisect.py", line 13, in perform_bisect
    bisector = api.create_bisector(bisect_config)
  File "E:\b\build\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\recipe_api.py", line 220, in _inner
    return func(*a, **kw)
  File "E:\b\build\scripts/slave\recipe_modules\auto_bisect\api.py", line 69, in create_bisector
    init_revisions=not dummy_mode)
  File "E:\b\build\scripts/slave\recipe_modules\auto_bisect\bisector.py", line 83, in __init__
    self._validate_config()
  File "E:\b\build\scripts/slave\recipe_modules\auto_bisect\bisector.py", line 218, in _validate_config
    config_validation.validate_bisect_config(self.bisect_config)
  File "E:\b\build\scripts/slave\recipe_modules\auto_bisect\config_validation.py", line 39, in validate_bisect_config
    validate_key(config, schema, key)
  File "E:\b\build\scripts/slave\recipe_modules\auto_bisect\config_validation.py", line 59, in validate_key
    _validate_integer(value, key)
  File "E:\b\build\scripts/slave\recipe_modules\auto_bisect\config_validation.py", line 85, in _validate_integer
    int(value)
TypeError: int() argument must be a string or a number, not 'NoneType'


Suspecting this CL
https://codereview.chromium.org/1782333002