AddonManager.jsm and XPIDatabase.jsm call several async functions without awaiting them, leading to races. This was found because bug 1649604 changed some timings (the overall number of execution context switches changed during a test run) causing test_update_theme.js to fail.

Backed out for failures on browser_1007336_lwthemes_in_customize_mode.js

backout: https://hg.mozilla.org/integration/autoland/rev/0c0c1834fbd1df9f0494306951626ace6b52e15b

push: https://treeherder.mozilla.org/jobs?repo=autoland&selectedTaskRun=J4offVFMRY2G9UHeMikKAQ.0&revision=db03ed8185997f681c2c9e2010a2c1c3bebb1344&group_state=expanded

failure log: https://treeherder.mozilla.org/logviewer?job_id=337179634&repo=autoland&lineNumber=2004

[task 2021-04-20T17:25:24.046Z] 17:25:24 INFO - TEST-PASS | browser/components/customizableui/test/browser_1007336_lwthemes_in_customize_mode.js | The fourth theme should be the alpenglow theme -
[task 2021-04-20T17:25:24.046Z] 17:25:24 INFO - Clicked on light theme
[task 2021-04-20T17:25:24.047Z] 17:25:24 INFO - Console message: 1618939518487 addons.webextension.firefox-compact-light@mozilla.org WARN Unrecognized theme property found: colors.panel_hover
[task 2021-04-20T17:25:24.047Z] 17:25:24 INFO - Console message: 1618939518488 addons.webextension.firefox-compact-light@mozilla.org WARN Unrecognized theme property found: colors.panel_active
[task 2021-04-20T17:25:24.047Z] 17:25:24 INFO - Console message: 1618939518488 addons.webextension.firefox-compact-light@mozilla.org WARN Unrecognized theme property found: colors.panel_active_darker
[task 2021-04-20T17:25:24.047Z] 17:25:24 INFO - Buffered messages finished
[task 2021-04-20T17:25:24.047Z] 17:25:24 INFO - TEST-UNEXPECTED-FAIL | browser/components/customizableui/test/browser_1007336_lwthemes_in_customize_mode.js | Uncaught exception - undefined - timed out after 50 tries.
[task 2021-04-20T17:25:24.047Z] 17:25:24 INFO - Leaving test bound
[task 2021-04-20T17:25:24.047Z] 17:25:24 INFO - Entering test bound asyncCleanup
[task 2021-04-20T17:25:24.147Z] 17:25:24 INFO - Leaving test bound asyncCleanup
[task 2021-04-20T17:25:24.187Z] 17:25:24 INFO - GECKO(9068) | MEMORY STAT | vsize 2104242MB | vsizeMaxContiguous 66249064MB | residentFast 265MB | heapAllocated 87MB
[task 2021-04-20T17:25:24.187Z] 17:25:24 INFO - TEST-OK | browser/components/customizableui/test/browser_1007336_lwthemes_in_customize_mode.js | took 6906ms

https://hg.mozilla.org/mozilla-central/rev/02a698f7345f

The patch landed in nightly and beta is affected.
:barret, is this bug important enough to require an uplift?
If not please set status_beta to wontfix.

For more information, please visit auto_nag documentation.

There is no need to fix this for beta. This was only required due to a subsequent patch in bug 1649604 causing test failures.