buildbot exception in on fop-trunk

[buildbot]

The Buildbot has detected a build exception on builder fop-trunk while building 
. Full details are available at:
    https://ci.apache.org/builders/fop-trunk/builds/1801

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

Buildslave for this Build: asf947_ubuntu

Build Reason: The Nightly scheduler named 'fopNightly' triggered this build
Build Source Stamp: [branch xmlgraphics/fop/trunk] HEAD
Blamelist: 

BUILD FAILED: exception compile MasterShellCommand_1

Sincerely,
 -The Buildbot