If you configure "Subversion Tagging" as action "After successful release build" the build is not tagged.
Console output is:
Building on master in workspace /data/jenkins/jobs/SVN-Jenkins-Test/workspace
at revision '2017-04-04T18:27:56.228 +0200'
At revision 3
No changes for
since the previous build
Starting to tag
No Subversion tagging for unsuccessful build.
If same configuration is used as post build action for the normal build, the repository is tagged correctly.