Because bug 1357049 jarred up UITour-lib.js unconditionally in the always-built browser/components/uitour/jar.mn but only referenced it in a test in the nightly-only browser/extensions/onboarding/, when we merge from mozilla-central to mozilla-beta on 2017-08-07 we'll have permaorange like https://treeherder.mozilla.org/logviewer.html#?job_id=108058722&repo=try [Tracking Requested - why for this release]: potential merge permaorange resulting in a closed tree and delayed b1.

Marking this as a blocking issue for 56 since it would potentially delay 56 beta 1. Marco or Fischer, can you help find someone to investigate and fix? Thanks.

Redirecting 'needinfo' to Francis who is EPM for Onboarding.

this issue will be discussed in onboarding daily standup, and the right person will handle this issue. thank you

Onboarding will be released in version 56. We should change build script such that Onboarding is built into firefox 56 beta and release. This error shell be cleared after the change. I'm also considering if we can build UITour-lib in Onboarding's package so that this won't happen even we don't build onboarding into Firefox. This should be possible but I'm not sure packaging files outside extension's directory is an allowed convention.

Hi Mossop: Given Onboarding is the only extension that uses UITour-lib.js which is originally a file not being packed anywhere, I think packaging it within onboarding may be a good idea to decouple whether we need to build onboarding with beta/release or not. The only thing I'm not sure about is whether we're allowed to package other components' file. So I just added some comments for that. Can you take a look whether this solution looks good to you?

Comment on attachment 8880320 [details] Bug 1374174 - Package UITour-lib.js only in onboarding extension to prevent noreference error. https://reviewboard.mozilla.org/r/151672/#review156902 Yes this seems like a good solution.

Thank you Mossop. https://treeherder.mozilla.org/#/jobs?repo=try&revision=83b45d3bbe57&selectedJob=109166336 It looks fine on try server so let's check it in.

Pushed by cbook@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/0913080e2c6a Package UITour-lib.js only in onboarding extension to prevent noreference error. r=mossop

How would I test this Rex? Seems like this is an automated test.

This is verified by the fact that this test isn't failing on Beta since 56 was uplifted there a week ago.