The incorrect order appears to be broken in production too, but I can't reproduce the slug issue in production.

I believe T182704 may be related to, or a duplicate of, this.

Change 399888 had a related patch set uploaded (by Catrope; owner: Catrope):
[VisualEditor/VisualEditor@master] Follow-up c7ef30a30f6: append multi-element nodes in the right order

https://gerrit.wikimedia.org/r/399888

In T183590#3857898, @Deskana wrote:

I believe T182704 may be related to, or a duplicate of, this.

Yes, pretty sure that's the same issue.

Change 399888 merged by jenkins-bot:
[VisualEditor/VisualEditor@master] Follow-up c7ef30a30f6: append multi-element nodes in the right order

https://gerrit.wikimedia.org/r/399888

In T183590#3858274, @gerritbot wrote:

Change 399888 merged by jenkins-bot:
[VisualEditor/VisualEditor@master] Follow-up c7ef30a30f6: append multi-element nodes in the right order

https://gerrit.wikimedia.org/r/399888

Given this merge, this should go out with the train this week, but also given this is an UBN!, should this be swatted to all wikis? @Catrope / @Deskana

Change 401599 had a related patch set uploaded (by Jforrester; owner: Jforrester):
[mediawiki/extensions/VisualEditor@master] Update VE core submodule to master (90a2a3834)

https://gerrit.wikimedia.org/r/401599

Change 401599 merged by jenkins-bot:
[mediawiki/extensions/VisualEditor@master] Update VE core submodule to master (8c5e78c7f)

https://gerrit.wikimedia.org/r/401599

In T183590#3868400, @Deskana wrote:

In T183590#3868053, @greg wrote:

Given this merge, this should go out with the train this week, but also given this is an UBN!, should this be swatted to all wikis? @Catrope / @Deskana

I don't think this needs a SWAT. The kinds of templates that cause this problem appear to be rarely used. In fact, I think this may have been broken for a while without anyone noticing.

This patch was in the VisualEditor/VisualEditor repo, which is not branched regularly – only mediawiki/extensions/VisualEditor is, and the submodule update commit (https://gerrit.wikimedia.org/r/401599) was not merged in time for wmf.15 (we had CI issues). I will be swatting this, especially since it resolves one more annoying issue too (T182907).

Change 401771 had a related patch set uploaded (by Bartosz Dziewoński; owner: Jforrester):
[mediawiki/extensions/VisualEditor@wmf/1.31.0-wmf.15] Update VE core submodule to master (8c5e78c7f)

https://gerrit.wikimedia.org/r/401771

Change 401771 merged by jenkins-bot:
[mediawiki/extensions/VisualEditor@wmf/1.31.0-wmf.15] Update VE core submodule to master (8c5e78c7f)

https://gerrit.wikimedia.org/r/401771

Mentioned in SAL (#wikimedia-operations) [2018-01-03T20:16:06Z] <thcipriani@tin> Synchronized php-1.31.0-wmf.15/extensions/VisualEditor/lib/ve: SWAT: [[gerrit:401771|Update VE core submodule to master]] T182907 T183590 (duration: 01m 06s)

Fixed and deployed to wmf.15.

Thank you!