reload traceback

[matthewrmshin]

Some users are experiencing suite shutdown on reload. The suite's log/suite/err shows this trace back:

  File "/opt/cylc-7.7.1/lib/cylc/scheduler.py", line 233, in start
    self.run()
  File "/opt/cylc-7.7.1/lib/cylc/scheduler.py", line 1379, in run
    if self.pool.release_runahead_tasks():
  File "/opt/cylc-7.7.1/lib/cylc/task_pool.py", line 314, in release_runahead_tasks
    if latest_allowed_point > self.stop_point:
  File "/opt/cylc-7.7.1/lib/cylc/cycling/iso8601.py", line 113, in __cmp__
    return self._iso_point_cmp(self.value, other.value)
  File "/opt/cylc-7.7.1/lib/cylc/cycling/iso8601.py", line 78, in _wrapper
    results = function(*args)
  File "/opt/cylc-7.7.1/lib/cylc/cycling/iso8601.py", line 152, in _iso_point_cmp
    other_point = point_parse(other_point_string)
  File "/opt/cylc-7.7.1/lib/cylc/cycling/iso8601.py", line 763, in point_parse
    return _point_parse(point_string).copy()
  File "/opt/cylc-7.7.1/lib/cylc/cycling/iso8601.py", line 78, in _wrapper
    results = function(*args)
  File "/opt/cylc-7.7.1/lib/cylc/cycling/iso8601.py", line 777, in _point_parse
    return SuiteSpecifics.point_parser.parse(point_string)
  File "/opt/cylc-7.7.1/lib/isodatetime/parsers.py", line 237, in parse
    date_info, time_info, parsed_expr = self.get_info(timepoint_string)
  File "/opt/cylc-7.7.1/lib/isodatetime/parsers.py", line 430, in get_info
    keys, date_info = self.get_date_info(date)
  File "/opt/cylc-7.7.1/lib/isodatetime/parsers.py", line 390, in get_date_info
    raise ISO8601SyntaxError("date", date_string)
ISO8601SyntaxError: Invalid ISO 8601 date representation: None

[matthewrmshin]

I have repeated this using this suite.

[cylc]
    cycle point format = %Y
[scheduling]
    initial cycle point = 2018
    max active cycle points = 2
    [[dependencies]]
        [[[P1Y]]]
            graph = t1[-P3Y] => t1
[runtime]
    [[t1]]
        script = sleep 60

1. cylc run SUITE
2. cylc stop --now SUITE
3. cylc restart SUITE
4. cylc reload SUITE would cause the suite to shut down the above traceback.

[hjoliver]

I tried your example suite. Reload works fine before but not after a restart, but the task pool content looks the same. cylc dump showed one difference:

Before restart:

status_string=running

After restart:

status_string=running to stop at None

That None looks suspicious...

[hjoliver]

(OK - ignore my comment, I just saw your PR!).