If I push to try requesting an artifact build, the resulting target has unofficial branding. If I request a non-artifact build I get Nightly branding. IMO they should both get unofficial branding since they're not Nightly builds. This causes problems for automated screenshot comparisons between try and m-c if the developer pushes to try requesting artifacts builds (either because their mozconfig specifies artifact builds or to get faster try results). See bug 1411640 comment 3 for an example[1] where this happened. By using unofficial branding for all non-Nightly automation builds, it's also more clear to a user running one of those builds that it's not a real Nightly. How I think macOS non-artifact builds end up with Nightly branding: https://dxr.mozilla.org/mozilla-central/rev/2535bad09d720e71a982f3f70dd6925f66ab8ec7/taskcluster/ci/build/macosx.yml#32,50 => https://dxr.mozilla.org/mozilla-central/rev/2535bad09d720e71a982f3f70dd6925f66ab8ec7/testing/mozharness/configs/builds/releng_base_mac_64_cross_builds.py#73 => https://dxr.mozilla.org/mozilla-central/rev/2535bad09d720e71a982f3f70dd6925f66ab8ec7/browser/config/mozconfigs/macosx64/nightly#20 [1] https://screenshots.mattn.ca/compare/?oldProject=mozilla-central&oldRev=40a14ca1cf04499f398e4cb8ba359b39eae4e216&newProject=try&newRev=6011efa03c457728a9d9b2caf10d0ee8eebc62f0

I dug into this a bit, and I found that bug 1157289 made it so that builds in automation used the nightly branding in order to distinguish themselves from locally produced builds. I consider this part of the 'shippable builds' proposal in bug 1352113. In that case we would do an unbranded "CI" build, and an officially branded "shippable" build.