Sometime after the 4.0 release we started getting an intermittent failure in CachingServiceTest in Travis CI. This test doesn't seem to fail on Bamboo (I've yet to see one fail).
This has nothing to do with the actual commit that is being tested, it must have been introduced by an earlier change. If you trigger a rebuild, it will usually go away (because it happens intermittently).
There have been no recent changes in the relevant test and tested class: