t4202-log.sh: Test git log --no-walk sort order

'git log --no-walk' sorts commits by commit time whereas 'git show' does
not (it leaves them as given on the command line). Document this by two
tests so that we never forget why ba1d450 (Tentative built-in "git
show", 2006-04-15) introduced it and 8e64006 (Teach revision machinery
about --no-walk, 2007-07-24) exposed it as an option argument.

Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t4202-log.sh

@@ -149,6 +149,26 @@ test_expect_success 'git log --follow' '
 
 '
 
+cat > expect << EOF
+804a787 sixth
+394ef78 fifth
+5d31159 fourth
+EOF
+test_expect_success 'git log --no-walk <commits> sorts by commit time' '
+	git log --no-walk --oneline 5d31159 804a787 394ef78 > actual &&
+	test_cmp expect actual
+'
+
+cat > expect << EOF
+5d31159 fourth
+804a787 sixth
+394ef78 fifth
+EOF
+test_expect_success 'git show <commits> leaves list of commits as given' '
+	git show --oneline -s 5d31159 804a787 394ef78 > actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'setup case sensitivity tests' '
 	echo case >one &&
 	test_tick &&