Merge branch 'jk/argv-array-for-child-process'

* jk/argv-array-for-child-process: argv-array: drop "detach" code get_importer: use run-command's internal argv_array get_exporter: use argv_array get_helper: use run-command's internal argv_array git_connect: use argv_array run_column_filter: use argv_array run-command: store an optional argv_array