As explained in JENKINS-14506, in some cases, the available configuration from the Jenkins administration screen is not enough.
I had to manually set user.email and user.name values on the local repository created by the plugin, being logged on the master server. It should be configurable from Jenkins UI.
Moreover, that issue means we have to undergo with a first recursive issue (see JENKINS-14564) for the repository being created before being able to manually fix it.