admin: .set cannot clear values

[HumorBaby]

The .set command of admin.py does not work as described.

sopel/sopel/modules/admin.py

Lines 252 to 263 in 824ae74

	@sopel.module.commands('set')
	@sopel.module.example('.set core.owner Me')
	def set_config(bot, trigger):
	"""See and modify values of Sopel's config object.
	Trigger args:
	arg1 - section and option, in the form "section.option"
	arg2 - value
	If there is no section, section will default to "core".
	If value is None, the option will be deleted.
	"""

says that if value is None, the option will be deleted. Currently, a None value does not get parsed properly, and the setting just ends up getting converted to a literal None string, as opposed to an actual NoneType.

I considered that the sentence meant that no value should be supplied, but that would preclude the See part of the See and modify values of Sopel's config object, where no argument should be provided for setting (which is working as expected). Thus, 🐛

---

Steps to replicate:

# admin_set_test.py

from __future__ import unicode_literals, absolute_import, division, print_function

from sopel.config.types import StaticSection, ValidatedAttribute
import sopel.module


class AdminSetTestSection(StaticSection):
    test_setting = ValidatedAttribute('test_setting', default=None)


def setup(bot):
    bot.config.define_section('admin_set_test', AdminSetTestSection)


@sopel.module.require_privmsg
@sopel.module.commands('ast-show')
def show(bot, trigger):
    bot.say('repr: "{}", type: "{}"'.format(
        repr(bot.config.admin_set_test.test_setting),
        type(bot.config.admin_set_test.test_setting)
    ))
    

# my-config.cfg
## Note: there is no `test_setting` set, so it defaults to `None` (`NoneType`)

[admin_set_test]

# _See_ current setting value
<HumorBaby>  .set admin_set_test.test_setting
<testbot>  HumorBaby: admin_set_test.test_setting = None

# See repr and type of setting
<HumorBaby>  .ast-show
<testbot>  repr: "None", type: "<type 'NoneType'>"

# Set a random value to setting
<HumorBaby>  .set admin_set_test.test_setting abc123

# Confirm change
<HumorBaby>  .set admin_set_test.test_setting
<testbot>  HumorBaby: admin_set_test.test_setting = abc123
<HumorBaby>  .ast-show
<testbot>  repr: "u'abc123'", type: "<type 'unicode'>"

# Try to "delete"/unset setting
<HumorBaby>  .set admin_set_test.test_setting None

# Confirm change
<HumorBaby>  .set admin_set_test.test_setting
<testbot>  HumorBaby: admin_set_test.test_setting = None
# everything looks okay...

# But wait... wat?
<HumorBaby>  .ast-show
<testbot>  repr: "u'None'", type: "<type 'unicode'>"

So, I wondered if .save'ing the config would somehow solve the issue...

<HumorBaby>  .save

# Restart bot here...

<HumorBaby>  .set admin_set_test.test_setting
<testbot>  HumorBaby: admin_set_test.test_setting = None
<HumorBaby>  .ast-show
<testbot>  repr: "'None'", type: "<type 'str'>"

Nope...