Trying to get a backtrace for T165074 using WMF machines was painful
I can't SSH to the ci-jessie-wikimedia-* machines, integration-slave-jessie-1001 only has hhvm-dev (no runtimes)... tin has hhvm, but php is default, and it doesn't have phpunit anyway...
One can't run MediaWiki PHPUnit tests on Beta-Cluster-Infrastructure , they write to the database/cache etc and are thus destructives.
Anyway, nowaday the way to reproduce a CI job is to use Quibble which has all the test logic. For a matching environment we have several Docker images for various environment which ship Quibble itself.
Some examples:
docker-registry.wikimedia.org/releng/quibble-jessie-php55
docker-registry.wikimedia.org/releng/quibble-jessie-hhvm
docker-registry.wikimedia.org/releng/quibble-stretch-php70
docker-registry.wikimedia.org/releng/quibble-stretch-php72
docker-registry.wikimedia.org/releng/quibble-jessie-php56
There is some documentation at https://doc.wikimedia.org/quibble/