Building PR on a CI server I observe that reports.html.displayName is reported as changed (in Appending inputPropertyHash for 'reports.html.displayName' to build cache key: ...) in 2 subsequent Jenkins builds from different branches with a change in source code only (not in Gradle configuration). I do not set it on my own (in API documentation it is marked as read-only anyway). This breaks caching as tests are executed.
Gradle 4.0.1 with Build cache enabled. The problem doesn’t occur when run locally with those branches.
What else can affect reports.html.displayName value?
I turned out that there was another similar task executed which was printed just before that task name. It’s really painful to explain some issues (for example with not cached tasks) if a build is executed in parallel on a CI machine with 32 vCPU… I reported a feature request to improve it - https://github.com/gradle/gradle/issues/2462.