buildbot exception in ASF Buildbot on flink-docs-release-0.10

[buildbot]

The Buildbot has detected a build exception on builder flink-docs-release-0.10 
while building ASF Buildbot. Full details are available at:
    http://ci.apache.org/builders/flink-docs-release-0.10/builds/64

Buildbot URL: http://ci.apache.org/

Buildslave for this Build: lares_ubuntu

Build Reason: The Nightly scheduler named 'flink-nightly-docs-release-0.10' 
triggered this build
Build Source Stamp: [branch release-0.10] HEAD
Blamelist: 

BUILD FAILED: exception git

Sincerely,
 -The Buildbot