reflog tests: assert lack of early exit with expiry="never"

When gc.reflogExpire and gc.reflogExpireUnreachable are set to "never"
and --stale-fix isn't in effect we *could* exit early without
pointlessly looping over all the reflogs.

However, as an earlier change to add a test for the "points nowhere"
warning shows even in such a mode we might want to print out a
warning.

So while it's conceivable to implement this, I don't think it's worth
it. It's going to be too easy to inadvertently add some flag that'll
make the expiry happen anyway, and even with "never" we'd like to see
all the lines we're going to keep.

So let's assert that we're going to loop over all the references even
when this configuration is in effect.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t1410-reflog.sh

@@ -235,7 +235,9 @@ test_expect_success 'gc.reflogexpire=never' '
 	test_config gc.reflogexpire never &&
 	test_config gc.reflogexpireunreachable never &&
 
-	git reflog expire --verbose --all &&
+	git reflog expire --verbose --all >output &&
+	test_line_count = 9 output &&
+
 	git reflog refs/heads/master >output &&
 	test_line_count = 4 output
 '