Merge branch 'ps/submodule-sanitize-path-upon-add'

"git submodule add" failed to squash "path/to/././submodule" to
"path/to/submodule".

* ps/submodule-sanitize-path-upon-add:
  git-submodule.sh: fix '/././' path normalization

diff --cc git-submodule.sh
Simple merge

diff --cc t/t7400-submodule-basic.sh
Simple merge