sys-apps/portage: 2.3.98-r1 revbump

sys-apps/portage: 2.3.98-r1 revbump

Fix this error:

Exception in callback Scheduler._schedule_merge_wakeup(<Future finished result=None>)
handle: <Handle Scheduler._schedule_merge_wakeup(<Future finished result=None>)>
Traceback (most recent call last):
  File "/usr/lib/python3.7/asyncio/events.py", line 88, in _run
    self._context.run(self._callback, *self._args)
  File "/usr/lib/python3.7/site-packages/_emerge/Scheduler.py", line 1638, in _schedule_merge_wakeup
    self._schedule()
  File "/usr/lib/python3.7/site-packages/_emerge/PollScheduler.py", line 154, in _schedule
    self._schedule_tasks()
  File "/usr/lib/python3.7/site-packages/_emerge/Scheduler.py", line 1615, in _schedule_tasks
    self._keep_scheduling() or self._main_exit.done()):
AttributeError: 'NoneType' object has no attribute 'done'

Reported-by: Rick Farina <zerochaos@gentoo.org>
Bug: https://bugs.gentoo.org/711148
Bug: https://bugs.gentoo.org/711322
Bug: https://bugs.gentoo.org/716636
Package-Manager: Portage-2.3.98, Repoman-2.3.22
Signed-off-by: Zac Medico <zmedico@gentoo.org>