git: branch not fully merged?

I am trying to delete a branch using gitbash and i get a error about the branch not being fully merged. Using TortoiseGit i merged, switch to master, tried merging again, commit then finally pull from the master and everything is fine. Yet git reports the branch not fully merged.

I think i am missing something. What is it?

The error msg

 warning(_("not deleting branch '%s' that is not yet merged to\n"
      "         '%s', even though it is merged to HEAD."),

After the origin (or another) branch pulls, pull from that branch even if nothing changed and you should be able to delete.