Merge branch 'rs/submodule-config-code-cleanup' into maint

Code cleanup. * rs/submodule-config-code-cleanup: submodule-config: fix test binary crashing when no arguments given submodule-config: combine early return code into one goto submodule-config: passing name reference for .gitmodule blobs submodule-config: use explicit empty string instead of strbuf in config_from()