Cannot remove branch in GitLab UI with git-flow naming convention

On 7.10 its no longer possible to remove a branch containing a / in his name. If you use use git-flow this is a very common naming. @stanhu already mentioned here: https://gitlab.com/gitlab-org/gitlab-ci/issues/145#note_1152827 that he fixed some bugs regarding encoding of / in Rails v4.1.9, maybe this is related to it.