[PATCH 1/3] sha1-file: test the error behavior of alt_odb_usable()

Add a test for the error() case in alt_odb_usable() where an alternate
directory doesn't exist. This behavior has been the same since
26125f6b9b ("detect broken alternates.", 2006-02-22), but if that
error() was turned into die() the entire test suite would still pass.

Perhaps we should die() in that case, but let's start by adding a test
here to assert the long-standing existing behavior.

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 t/t5613-info-alternate.sh | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/t/t5613-info-alternate.sh b/t/t5613-info-alternate.sh
index 895f46bb91..d2964c57b7 100755
--- a/t/t5613-info-alternate.sh
+++ b/t/t5613-info-alternate.sh

@@ -136,4 +136,11 @@ test_expect_success CASE_INSENSITIVE_FS 'dup finding can be case-insensitive' '
 	test_cmp expect actual.alternates
 '
 
+test_expect_success 'print "error" on non-existing alternate' '
+	git init --bare I &&
+	echo DOES_NOT_EXIST >I/objects/info/alternates &&
+	git -C I fsck 2>stderr &&
+	test_i18ngrep "does not exist; check" stderr
+'
+
 test_done

-- 
2.20.0.rc2.403.gdbc3b29805