tests: correct "does reflog exist?" tests

These two tests weren't about how "git reflog show <branch>" exits when
there is no reflog, but were about "checkout" and "branch" create or not
create reflog when creating a new <branch>.  Update the tests to check
what we are interested in, using "git rev-parse --verify".

Also lose tests based on "test -f .git/logs/refs/heads/<branch>" from
nearby, to avoid exposing this particular implementation detail
unnecessarily.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t2017-checkout-orphan.sh

diff --git a/t/t2017-checkout-orphan.sh b/t/t2017-checkout-orphan.sh
index 81cb393..2d2f63f 100755
--- a/t/t2017-checkout-orphan.sh
+++ b/t/t2017-checkout-orphan.sh
@@ -68,65 +68,34 @@
 	git checkout master &&
 	git config --unset core.logAllRefUpdates &&
 	git checkout --orphan delta &&
-	! test -f .git/logs/refs/heads/delta &&
-	(
-		PAGER= &&
-		export PAGER &&
-		test_must_fail git reflog show delta
-	) &&
+	test_must_fail git rev-parse --verify delta@{0} &&
 	git commit -m Delta &&
-	test -f .git/logs/refs/heads/delta &&
-	PAGER= git reflog show delta
+	git rev-parse --verify delta@{0}
 '
 
 test_expect_success '--orphan does not make reflog when core.logAllRefUpdates = false' '
 	git checkout master &&
 	git config core.logAllRefUpdates false &&
 	git checkout --orphan epsilon &&
-	! test -f .git/logs/refs/heads/epsilon &&
-	(
-		PAGER= &&
-		export PAGER &&
-		test_must_fail git reflog show epsilon
-	) &&
+	test_must_fail git rev-parse --verify epsilon@{0} &&
 	git commit -m Epsilon &&
-	! test -f .git/logs/refs/heads/epsilon &&
-	(
-		PAGER= &&
-		export PAGER &&
-		test_must_fail git reflog show epsilon
-	)
+	test_must_fail git rev-parse --verify epsilon@{0}
 '
 
 test_expect_success '--orphan with -l makes reflog when core.logAllRefUpdates = false' '
 	git checkout master &&
 	git checkout -l --orphan zeta &&
-	test -f .git/logs/refs/heads/zeta &&
-	(
-		PAGER= &&
-		export PAGER &&
-		test_must_fail git reflog show zeta
-	) &&
+	test_must_fail git rev-parse --verify zeta@{0} &&
 	git commit -m Zeta &&
-	PAGER= git reflog show zeta
+	git rev-parse --verify zeta@{0}
 '
 
 test_expect_success 'giving up --orphan not committed when -l and core.logAllRefUpdates = false deletes reflog' '
 	git checkout master &&
 	git checkout -l --orphan eta &&
-	test -f .git/logs/refs/heads/eta &&
-	(
-		PAGER= &&
-		export PAGER &&
-		test_must_fail git reflog show eta
-	) &&
+	test_must_fail git rev-parse --verify eta@{0} &&
 	git checkout master &&
-	! test -f .git/logs/refs/heads/eta &&
-	(
-		PAGER= &&
-		export PAGER &&
-		test_must_fail git reflog show eta
-	)
+	test_must_fail git rev-parse --verify eta@{0}
 '
 
 test_expect_success '--orphan is rejected with an existing name' '

t/t3200-branch.sh

diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
index bf7747d..f54a533 100755
--- a/t/t3200-branch.sh
+++ b/t/t3200-branch.sh
@@ -228,28 +228,21 @@
 	git checkout master &&
 	git config --unset core.logAllRefUpdates &&
 	git checkout -b alpha &&
-	test -f .git/logs/refs/heads/alpha &&
-	PAGER= git reflog show alpha
+	git rev-parse --verify alpha@{0}
 '
 
 test_expect_success 'checkout -b does not make reflog when core.logAllRefUpdates = false' '
 	git checkout master &&
 	git config core.logAllRefUpdates false &&
 	git checkout -b beta &&
-	! test -f .git/logs/refs/heads/beta &&
-	(
-		PAGER= &&
-		export PAGER &&
-		test_must_fail git reflog show beta
-	)
+	test_must_fail git rev-parse --verify beta@{0}
 '
 
 test_expect_success 'checkout -b with -l makes reflog when core.logAllRefUpdates = false' '
 	git checkout master &&
 	git checkout -lb gamma &&
 	git config --unset core.logAllRefUpdates &&
-	test -f .git/logs/refs/heads/gamma &&
-	PAGER= git reflog show gamma
+	git rev-parse --verify gamma@{0}
 '
 
 test_expect_success 'avoid ambiguous track' '