Jenkins "Git plugin" neither ignores commits with certain messages nor commits with from certain users
There is a current fix in progress at JENKINS-25048, with PR 318
That could be enough for git polling to ignores what it is supposed to.
Note: there is a similar bug with pipelines.
It seems that the plugin is not filtering your commits (which have to be ignored); and hence triggers a build on these commits.
Check the regex to filter specific commits that you have set in the plugin.
It seems that Jenkins "polling ignores commits from certain users","polling ignores commits with certain messages" and "polling ignores commits in certain paths" ignores the merge commits.Also it seems that even the changelogs does not have any "merge" commits.