Apparently the setting 'gitoliteIdentityFile' is completely ignored by redmine-gitolite. The old redmine-gitosis did all sorts of tricks with GIT_SSH that were removed in redmine-gitolite.

With redmine-gitolite, the installation involves creating a redmine user and making passenger use that user, also adding redmine to the git user group, etc.

I suggest you remove the gitoliteIdentityFile option completely for now and maybe create a nice "how to install" instead.