Merge branch 'bw/submodule-has-commits-update'

Code clean-up and duplicate removal. * bw/submodule-has-commits-update: submodule: refactor logic to determine changed submodules submodule: improve submodule_has_commits() submodule: change string_list changed_submodule_paths submodule: remove add_oid_to_argv() submodule: rename free_submodules_sha1s() submodule: rename add_sha1_to_array()