On a slave machine there was a global git config option set to always use color ui.

git config --global color.ui always

This caused the generated changelog.xml file to contain escape characters. An example is shown below ..

ESC[33mcommit 6c5abba0f9c1e91a2635bad606e3321121e3deadESC[m
tree 600d0558f2b45d82128e467dd5b7e5fbf7851f78
parent c976b4ab633e7b3b0f03c55ddc76409601bdc134
author Matt Byrne <matt.byrne@example.com> 1421118701 +1100
committer Matt Byrne <matt.byrne@example.com> 1421118701 +1100

    Dummy change to test jenkins

:100644 100644 1f71f9286164ed2965f3004a30501698b9f2eefc ae0c99d78b06ae9714a23aee796f9f2585b8899b M      build.gradle

When you view a build in Jenkins you will always see No Changes. This is happening on any version of Jenkins that I can remember seeing in the last couple of years ... only just figured out why.

The obvious workaround is to not use that git option, set it to auto (that's the default anyway) or set it to false.