Merge branch 'dl/test-must-fail-fixes-4'

Test clean-up. * dl/test-must-fail-fixes-4: t9819: don't use test_must_fail with p4 t9164: use test_must_fail only on git commands t9160: use test_path_is_missing() t9141: use test_path_is_missing() t7508: don't use `test_must_fail test_cmp` t7408: replace incorrect uses of test_must_fail t6030: use test_path_is_missing()