Filed by: rmaries [at] mozilla.com
Parsed log: https://treeherder.mozilla.org/logviewer?job_id=320651227&repo=autoland
Full log: https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/ZTZBROZ7SmSD0ravgLQOpQ/runs/0/artifacts/public/logs/live_backing.log

[task 2020-11-03T22:49:56.147Z] 22:49:56     INFO - TEST-START | layout/base/tests/marionette/test_accessiblecaret_cursor_mode.py AccessibleCaretCursorModeTestCase.test_caret_not_jump_when_dragging_to_editable_content_boundary_input_padding
[task 2020-11-03T22:49:57.024Z] 22:49:57     INFO -  1604443797022	Marionette	DEBUG	13 <- [1,37,null,{"value":null}]
[task 2020-11-03T22:49:57.069Z] 22:49:57     INFO -  1604443797024	Marionette	DEBUG	13 -> [0,38,"WebDriver:TakeScreenshot",{"full":true,"hash":false,"id":null,"scroll":true}]
[task 2020-11-03T22:49:57.156Z] 22:49:57     INFO - TEST-UNEXPECTED-ERROR | layout/base/tests/marionette/test_accessiblecaret_cursor_mode.py AccessibleCaretCursorModeTestCase.test_caret_not_jump_when_dragging_to_editable_content_boundary_input_padding | KeyError: '-1'
[task 2020-11-03T22:49:57.156Z] 22:49:57     INFO - Traceback (most recent call last):
[task 2020-11-03T22:49:57.156Z] 22:49:57     INFO -   File "/Users/cltbld/tasks/task_1604441629/build/venv/lib/python2.7/site-packages/marionette_harness/marionette_test/testcases.py", line 214, in run
[task 2020-11-03T22:49:57.156Z] 22:49:57     INFO -     testMethod()
[task 2020-11-03T22:49:57.156Z] 22:49:57     INFO -   File "/Users/cltbld/tasks/task_1604441629/build/venv/lib/python2.7/site-packages/marionette_harness/marionette_test/testcases.py", line 64, in wrapper
[task 2020-11-03T22:49:57.157Z] 22:49:57     INFO -     return func(self, *args, **kwargs)
[task 2020-11-03T22:49:57.157Z] 22:49:57     INFO -   File "/Users/cltbld/tasks/task_1604441629/build/tests/marionette/tests/layout/base/tests/marionette/test_accessiblecaret_cursor_mode.py", line 188, in test_caret_not_jump_when_dragging_to_editable_content_boundary
[task 2020-11-03T22:49:57.157Z] 22:49:57     INFO -     x, y = sel.first_caret_location()
[task 2020-11-03T22:49:57.157Z] 22:49:57     INFO -   File "/Users/cltbld/tasks/task_1604441629/build/tests/marionette/tests/layout/base/tests/marionette/selection.py", line 262, in first_caret_location
[task 2020-11-03T22:49:57.157Z] 22:49:57     INFO -     return self.carets_location()[0]
[task 2020-11-03T22:49:57.157Z] 22:49:57     INFO -   File "/Users/cltbld/tasks/task_1604441629/build/tests/marionette/tests/layout/base/tests/marionette/selection.py", line 244, in carets_location
[task 2020-11-03T22:49:57.157Z] 22:49:57     INFO -     return self._selection_location_helper("caret")
[task 2020-11-03T22:49:57.157Z] 22:49:57     INFO -   File "/Users/cltbld/tasks/task_1604441629/build/tests/marionette/tests/layout/base/tests/marionette/selection.py", line 196, in _selection_location_helper
[task 2020-11-03T22:49:57.157Z] 22:49:57     INFO -     last_rect_list[str(last_list_length - 1)],
[task 2020-11-03T22:49:57.157Z] 22:49:57     INFO - TEST-INFO took 978ms
[task 2020-11-03T22:49:57.157Z] 22:49:57     INFO -  1604443797112	Marionette	DEBUG	13 <- [1,38,null,{"value":"iVBORw0KGgoAAAANSUhEUgAABQAAAAPpCAYAAABKf4CHAAAgAElEQVR4nOzdeVhU970/8PPPfZ57bzu3SwyJCU1a0pLqbWhjYn5pvTaa ... AAAAAAGBOAAAAAADAmAAEAAABgTAACAAAAwJgABAAAAIAxAQgAAAAAYwIQAAAAAMYEIAAAAACMCUAAAAAAGBOAAAAAADAWQXuSUgbbWRkAAAAASUVORK5CYII="}]
[task 2020-11-03T22:49:57.157Z] 22:49:57     INFO -  1604443797114	Marionette	DEBUG	13 -> [0,39,"Marionette:SetContext",{"value":"content"}]```

https://wiki.mozilla.org/Bug_Triage#Intermittent_Test_Failure_Cleanup
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