Fixes <https://bugs.gnu.org/23697>. Reported by Jan Nieuwenhuizen <janneke@gnu.org>. * gnu/build/file-systems.scm (check-file-system): Call 'start-repl' only if current-input-port passes 'isatty?'. * gnu/services/shepherd.scm (shepherd-configuration-file): After 'for-each' expression, call 'redirect-port'. * gnu/tests/base.scm (run-basic-test)["stdin is /dev/null"]: New test.