buildbot exception in ASF Buildbot on flink-docs-release-0.8

The Buildbot has detected a build exception on builder flink-docs-release-0.8 while building ASF Buildbot. Full details are available at: http://ci.apache.org/builders/flink-docs-release-0.8/builds/56 Buildbot URL: http://ci.apache.org/ Buildslave for this Build: orcus_ubuntu Build Reason:

buildbot success in ASF Buildbot on flink-docs-master

The Buildbot has detected a restored build on builder flink-docs-master while building ASF Buildbot. Full details are available at: http://ci.apache.org/builders/flink-docs-master/builds/75 Buildbot URL: http://ci.apache.org/ Buildslave for this Build: orcus_ubuntu Build Reason: The Nightly