Merge branch 'js/mv-dir-to-new-directory' into maint

"git mv dir non-existing-dir/" did not work in some environments the same way as existing mainstream platforms. The code now moves "dir" to "non-existing-dir", without relying on rename("A", "B/") that strips the trailing slash of '/'. * js/mv-dir-to-new-directory: git mv: do not keep slash in `git mv dir non-existing-dir/`