After some analysis I think this is the Wagon upgrade to 2.10 in Maven 3.3.9
I have created a mng-3599 branch in maven-integration-tests with my proposed fix (namely deactivate the old test from 3.3.9 onwards and duplicate with a new test for 3.3.9 onwards I have committed a throw-away branch in maven-core called mng-3599 with the Jenkinsfile pointing at the mng-3599 integration tests... Let's see if that fixes our test for us: https://builds.apache.org/job/maven-jenkinsfile/job/mng-3599/