Merge branch 'rs/test-cleanup'

Test cleanup. * rs/test-cleanup: t7811: don't create unused file t9300: don't create unused file test: use test_must_be_empty F instead of test_cmp empty F test: use test_must_be_empty F instead of test -z $(cat F) t1400: use test_must_be_empty t1410: use test_line_count t1512: use test_line_count