Bug 187120

Today I noticed that the style-queue raised an exception when trying to process a security-sensitive attachment:

2018-06-27 11:31:01,380 - Fetching next work item for style-queue
2018-06-27 11:31:01,752 - Fetching: https://bugs.webkit.org/attachment.cgi?id=343639&action=edit
2018-06-27 11:31:01,950 - You don't have permission to view this attachment.
2018-06-27 11:31:01,951 - Fetching: https://webkit-queues.webkit.org/attachment/metadata/343639
2018-06-27 11:31:02,275 - Fetching: https://webkit-queues.webkit.org/attachment/data/343639
2018-06-27 11:31:02,500 - Started processing patch
2018-06-27 11:31:03,057 - Fetching: https://bugs.webkit.org/attachment.cgi?id=343639&action=edit
2018-06-27 11:31:03,248 - You don't have permission to view this attachment.
2018-06-27 11:31:03,248 - Unable to parse bug_id from attachment 343639 [details]
Traceback (most recent call last):
  File "/Volumes/.../Tools/Scripts/webkitpy/tool/bot/queueengine.py", line 103, in run
    if not self._delegate.process_work_item(work_item):
  File "/Volumes/.../Tools/Scripts/webkitpy/tool/commands/queues.py", line 467, in process_work_item
    passed = self.review_patch(patch)
  File "/Volumes/.../Tools/Scripts/webkitpy/tool/commands/queues.py", line 491, in review_patch
    style_check_succeeded = task.run()
  File "/Volumes/.../Tools/Scripts/webkitpy/tool/bot/stylequeuetask.py", line 69, in run
    if not self._clean():
  File "/Volumes/.../Tools/Scripts/webkitpy/tool/bot/patchanalysistask.py", line 113, in _clean
    "Unable to clean working directory")
  File "/Volumes/.../Tools/Scripts/webkitpy/tool/bot/patchanalysistask.py", line 97, in _run_command
    if not self.validate():
  File "/Volumes/.../Tools/Scripts/webkitpy/tool/bot/stylequeuetask.py", line 40, in validate
    if self._patch.is_obsolete():
AttributeError: 'NoneType' object has no attribute 'is_obsolete'