prepare uses SNAPSHOT tag names

Preparing a release with the latest 2.2 version of this plugin generates a tag with the SNAPSHOT version of the project I want to prepare.
E.g. my project has is called sushi, and the current version is 2.6.0-SNAPSHOT. When I prepare the release, I expect a tag "sushi-2.6.0", but the tag I get ist sushi-2.6.0-SNAPSHOT.