When ${gitlab_development_root} is a path to a folder under '/home/git',
the last part of the sed call replaced '/home/git' twice.

E.g. gitlab_development_root='/home/git/gitlab-dev-kit' results in
socket_path='/home/git/gitlab-dev-kit/gitlab-dev-kit/gitaly.socket', which
does not exist.

Note that it is the first command of all other similar sed commands in
the Makefile.