Jenkins marks a maven release build as having failed when the job has been configured to use the emma reports plugin and the maven release build is configured to run -Dresume=false release:prepare release:perform. The emma plugin logs the following:

Emma: no coverage files found in workspace. Was any report generated?
Build step 'Record Emma coverage report' changed build result to FAILURE

There should be a way to disable the emma plugin from running when doing a release, or do not have it fail the release build.

A work around is to include emma:emma in the "Release goals and options" when configuring the job.