Apparently only affects 5.10, and maybe 5.11.

See https://hibernate.zulipchat.com/#narrow/stream/132095-hibernate-infra/topic/Jenkins.20update/near/357569321

Seems similar to https://issues.jenkins.io/browse/JENKINS-49413, but different: the Jenkins plugin assumes the path is absolute and tries to make it relative, even when it's already relative...