Cannot hash built-in function max

[albertz]

...
  File "/rwthfs/rz/cluster/home/az668407/setups/combined/2021-05-31/tools/sisyphus/sisyphus/hash.py", line 162, in sis_hash_helper
    line: byte_list.append(sis_hash_helper(get_object_state(obj)))
    locals:
      byte_list = <local> [b'DelayedFunction'], _[0]: {len = 15}
      obj = <local> 74.985
  File "/rwthfs/rz/cluster/home/az668407/setups/combined/2021-05-31/tools/sisyphus/sisyphus/hash.py", line 147, in sis_hash_helper
    line: byte_list += sorted(map(sis_hash_helper, obj.items()))
    locals:
      byte_list = <local> [b'dict'], _[0]: {len = 4}
      obj = <local> {'func': <built-in function max>, 'string': 74.985, 'args': (3,), 'kwargs': {}}
  File "/rwthfs/rz/cluster/home/az668407/setups/combined/2021-05-31/tools/sisyphus/sisyphus/hash.py", line 142, in sis_hash_helper
    line: byte_list += map(sis_hash_helper, obj)
    locals:
      byte_list = <local> [b'tuple', b"(str, 'func')"], _[0]: {len = 5}
      obj = <local> ('func', <built-in function max>)
  File "/rwthfs/rz/cluster/home/az668407/setups/combined/2021-05-31/tools/sisyphus/sisyphus/hash.py", line 162, in sis_hash_helper
    line: byte_list.append(sis_hash_helper(get_object_state(obj)))
    locals:
      byte_list = <local> [b'builtin_function_or_method'], _[0]: {len = 26}
      obj = <local> <built-in function max>
  File "/rwthfs/rz/cluster/home/az668407/setups/combined/2021-05-31/tools/sisyphus/sisyphus/hash.py", line 105, in get_object_state
    line: assert args is not None, "Failed to get object state of: %s" % repr(obj)
    locals:
      args = <local> None
      obj = <local> <built-in function max>
AssertionError: Failed to get object state of: <built-in function max>

That was triggered via this code:

def _clamp_hours(hours: DelayedBase, min_hours: float = 3) -> DelayedBase:
    return DelayedFunction(hours, max, min_hours)

[michelwi]

I think the function max should have gone the path

    if isfunction(obj) or isclass(obj):
        return obj.__module__, obj.__qualname__`

But isfunction does not seem to detect builtin functions written in C. I think we should use inspect.isroutine instead.
Maybe also check if needed in sis_hash_helper