Merge branch 'sb/submodule-module-list-fix' into maint

A helper function "git submodule" uses since v2.7.0 to list the
modules that match the pathspec argument given to its subcommands
(e.g. "submodule add <repo> <path>") has been fixed.

* sb/submodule-module-list-fix:
  submodule helper list: respect correct path prefix