When doing a release for a Maven build project (using the m2release plugin), the build user vars gets screwed up in the Maven build during the Maven build execution triggered by release:perform.
BUILD_USER is set to the user id ('kaha14' for example). BUILD_USER_ID is not set. BUILD_USER_FIRST_NAME is set to the same as BUILD_USER and BUILD_USER_LAST_NAME is not set (probably because BUILD_USER is just one word).