The android-gradle-build python tests run artifact builds, but
`mach artifact install` only searches the `.shippable` index for opt
builds. For each of the 50 candidate pushheads it looks up
`gecko.v2.autoland.shippable.revision.<rev>.mobile.android-<arch>-opt`.
Shippable Android builds aren't scheduled by default on autoland, so when
none of the last 50 autoland pushes ran a shippable build, the search
comes up empty, fails with "no built artifacts found", and every
artifact-build test in the suite fails at once. It passes only when one
of those 50 pushes happens to have a shippable Android build, which is
why it shows up as an intermittent.
Add a MOZ_ARTIFACT_ALLOW_NON_SHIPPABLE environment variable that makes
the index lookup fall back to the regular per-push opt build when no
shippable build is found, and set it for the android-gradle-build task.
The shippable index is still tried first, so branches that only publish
shippable builds (central, beta, release, esr) keep resolving to those.
Differential Revision: https://phabricator.services.mozilla.com/D324866
Julien Cristau
e10bbf0dae