Well, I cannot access my old ticket and new ReviewBot category is not selectable. Private?
What version are you running?
RB 3.0.2

ReviewBot master
What's the URL of the page containing the problem?
http://localhost/admin/integrations/reviewbotext.integration.ReviewBotIntegration/configs/8/

What steps will reproduce the problem?

Install ReviewBot Extension
Configure a checker and start worker
Go to http://localhost/admin/extensions/reviewbotext.extension.ReviewBotExtension/db/reviewbotext/tool/
Remove all tools
Press "Refresh installed Tools"
List is complete again
Go to link above: configuration of a checker
Error 500 (stacktrace below)


What is the expected output? What do you see instead?
The site of the configuration. Of course with a warning if there is no checker with the configured version anymore. But it should not be wiped because I refreshed the database and lost v1.0 checker because worker upgraded to v1.1!

Please provide any additional information below.
2018-01-20 00:44:01,393 - DEBUG -  - amqp - Start from server, version: 0.9, properties: {u'information': u'Licensed under the MPL.  See http://www.rabbitmq.com/', u'product': u'RabbitMQ', u'copyright': u'Copyright (C) 2007-2017 Pivotal Software, Inc.', u'capabilities': {u'exchange_exchange_bindings': True, u'connection.blocked': True, u'authentication_failure_close': True, u'direct_reply_to': True, u'basic.nack': True, u'per_consumer_qos': True, u'consumer_priorities': True, u'consumer_cancel_notify': True, u'publisher_confirms': True}, u'cluster_name': u'rabbit@rabbit', u'platform': u'Erlang/OTP 20.1.7', u'version': u'3.7.2'}, mechanisms: [u'PLAIN', u'AMQPLAIN'], locales: [u'en_US']

2018-01-20 00:44:01,394 - DEBUG -  - amqp - Open OK!

2018-01-20 00:44:01,394 - DEBUG -  - amqp - using channel_id: 1

2018-01-20 00:44:01,395 - DEBUG -  - amqp - Channel open

2018-01-20 00:44:11,439 - ERROR - None - admin - /admin/integrations/reviewbotext.integration.ReviewBotIntegration/configs/8/ - djblets.log.middleware - Exception thrown for user admin at http://localhost/admin/integrations/reviewbotext.integration.ReviewBotIntegration/configs/8/
[u'Tool with pk 22 does not exist']

Traceback (most recent call last):

  File "/var/www/dist/lib/python2.7/site-packages/django/core/handlers/base.py", line 112, in get_response

    response = wrapped_callback(request, callback_args, callback_kwargs)

  File "/var/www/dist/lib/python2.7/site-packages/django/views/generic/base.py", line 69, in view

    return self.dispatch(request, *args, kwargs)

  File "/var/www/dist/lib/python2.7/site-packages/django/utils/decorators.py", line 29, in _wrapper

    return bound_func(args, kwargs)

  File "/var/www/dist/lib/python2.7/site-packages/django/contrib/admin/views/decorators.py", line 17, in _checklogin

    return view_func(request, *args, kwargs)

  File "/var/www/dist/lib/python2.7/site-packages/django/utils/decorators.py", line 25, in bound_func

    return func(self, args2, kwargs2)

  File "/var/www/dist/lib/python2.7/site-packages/djblets/integrations/views.py", line 352, in dispatch

    *args, kwargs)

  File "/var/www/dist/lib/python2.7/site-packages/django/utils/decorators.py", line 29, in _wrapper

    return bound_func(args, kwargs)

  File "/var/www/dist/lib/python2.7/site-packages/django/contrib/auth/decorators.py", line 22, in _wrapped_view

    return view_func(request, *args, kwargs)

  File "/var/www/dist/lib/python2.7/site-packages/django/utils/decorators.py", line 25, in bound_func

    return func(self, args2, kwargs2)

  File "/var/www/dist/lib/python2.7/site-packages/django/utils/decorators.py", line 29, in _wrapper

    return bound_func(*args, kwargs)

  File "/var/www/dist/lib/python2.7/site-packages/django/utils/decorators.py", line 99, in _wrapped_view

    response = view_func(request, args, kwargs)

  File "/var/www/dist/lib/python2.7/site-packages/django/utils/decorators.py", line 25, in bound_func

    return func(self, *args2, kwargs2)

  File "/var/www/dist/lib/python2.7/site-packages/djblets/integrations/views.py", line 194, in dispatch

    request, args, kwargs)

  File "/var/www/dist/lib/python2.7/site-packages/django/views/generic/base.py", line 87, in dispatch

    return handler(request, *args, kwargs)

  File "/var/www/dist/lib/python2.7/site-packages/django/views/generic/edit.py", line 160, in get

    form = self.get_form(form_class)

  File "/var/www/dist/lib/python2.7/site-packages/django/views/generic/edit.py", line 44, in get_form

    return form_class(self.get_form_kwargs())

  File "/var/www/dist/lib/python2.7/site-packages/reviewbotext/forms.py", line 74, in init

    super(ReviewBotConfigForm, self).init(*args, kwargs)

  File "/var/www/dist/lib/python2.7/site-packages/reviewboard/integrations/forms.py", line 58, in init

    super(IntegrationConfigForm, self).init(args, kwargs)

  File "/var/www/dist/lib/python2.7/site-packages/djblets/integrations/forms.py", line 75, in init

    super(IntegrationConfigForm, self).init(*args, kwargs)

  File "/var/www/dist/lib/python2.7/site-packages/djblets/forms/forms/key_value_form.py", line 113, in init

    self.load()

  File "/var/www/dist/lib/python2.7/site-packages/reviewbotext/forms.py", line 88, in load

    super(ReviewBotConfigForm, self).load()

  File "/var/www/dist/lib/python2.7/site-packages/djblets/forms/forms/key_value_form.py", line 136, in load

    value = deserialize_func(value)

  File "/var/www/dist/lib/python2.7/site-packages/reviewbotext/forms.py", line 123, in deserialize_tool_field

    raise ValidationError('Tool with pk %s does not exist' % value)

ValidationError: [u'Tool with pk 22 does not exist']