TEST-UNEXPECTED-FAIL | Z:\task_1555759765\build\tests\mozmill\eventDialog\testEventDialogModificationPrompt.js | testEventDialogModificationPrompt.js::testEventDialogModificationPrompt

https://taskcluster-artifacts.net/fxVO8D_8StmZyp57hims7w/0/public/logs/live_backing.log
EXCEPTION: Expression "{"attendeeid":"mailto:foo@bar.de"}" returned null. Anonymous == false

As far as I can tell, first seen here, Sat, Apr 20, 11:51:34:
https://treeherder.mozilla.org/#/jobs?repo=comm-central&revision=38b96cc589cea8d29b5d723a7b1e79d77cb650ba&selectedJob=241597487

That's long after the attendee bug landed: Bug 1522473 - 2019-04-17.

It's also before bug 1509837 and bug 1511270 and bug 1523424 landed. So I can't blame any of those four.

In any case, Arshad and Magnus, can you please take a look.

Seems pretty perma-red on Windows, but intermittent on Linux64, for example present here:
https://treeherder.mozilla.org/#/jobs?repo=comm-central&revision=01f7fa7837622797bb47ded40d93eb2c6b157023&selectedJob=241634485
But not on the Daily on the same changeset.

This was hiding behind the testEventDialog.js timeout. I did a try run based on 72eadf95a120 but with testEventDialog.js disabled.

The push before was clear.

So the regression is somewhere here: https://hg.mozilla.org/comm-central/pushloghtml?fromchange=1552305b49b0&tochange=72eadf95a120

If the regression is that range on Apr 17th (and the scroll-container binding stuff was also backed out in there), why did it first show on 20th? There is no sight of it on the 18th:
https://treeherder.mozilla.org/#/jobs?repo=comm-central&revision=1e9b60bd5e340a500fe97f5618d948dcdeed40b6

Maybe it would be easiest to just check where/why the test is failing?

OK, well, on a second look, this is the failure we're looking for:
https://treeherder.mozilla.org/#/jobs?repo=try-comm-central&revision=ce4ff9f81da7f71cc3a182c4ffab9ad840414866&selectedJob=241920641
Since bug 1509837 was already backed out, it must have been bug 1512805, but it's still unclear why that got aggravated more later.

EDIT: And lately, it's only failing on Windows.

I ll take a look at this soon.

Sorry, I have to disable this, it's causing too much disruption since it leaves a prompt open when crashes the entire Mozmill directory.

This test passes and can be re-enabled. Probably fixed by bug 1551110.

Pushed by mozilla@jorgk.com:
https://hg.mozilla.org/comm-central/rev/c104316e6c21
Backed out changeset 64481201ec54 to re-enable test. a=backout DONTBUILD

https://hg.mozilla.org/releases/comm-beta/rev/5962a6e286d9b1826029dd449dd4dd638226aa2f