Update gitlab_git to ignore invalid lines in .gitmodules.
Pulls in gitlab_git 7.1.9 which contains https://gitlab.com/gitlab-org/gitlab_git/merge_requests/24
Closes #1412 (closed), https://github.com/gitlabhq/gitlabhq/issues/8135 and https://github.com/gitlabhq/gitlabhq/issues/8881