Merge branch 'dl/t5520-cleanup'

Test cleanup. * dl/t5520-cleanup: t5520: replace `! git` with `test_must_fail git` t5520: remove redundant lines in test cases t5520: replace $(cat ...) comparison with test_cmp t5520: don't put git in upstream of pipe t5520: test single-line files by git with test_cmp t5520: use test_cmp_rev where possible t5520: replace test -{n,z} with test-lib functions t5520: use test_line_count where possible t5520: remove spaces after redirect operator t5520: replace test -f with test-lib functions t5520: let sed open its own input t5520: use sq for test case names t5520: improve test style t: teach test_cmp_rev to accept ! for not-equals t0000: test multiple local assignment