[PATCH 5/6] fsck: do not fallback "git fsck <bogus>" to "git fsck"

[Jeff King <peff@peff.net>]

Since fsck tries to continue as much as it can after seeing
an error, we still do the reachability check even if some
heads we were given on the command-line are bogus. But if
_none_ of the heads is is valid, we fallback to checking all
refs and the index, which is not what the user asked for at
all.

Instead of checking "heads", the number of successful heads
we got, check "argc" (which we know only has non-options in
it, because parse_options removed the others).

Signed-off-by: Jeff King <peff@peff.net>
---
 builtin/fsck.c  |  2 +-
 t/t1450-fsck.sh | 11 +++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/builtin/fsck.c b/builtin/fsck.c
index c7d0590e5..8ae065b2d 100644
--- a/builtin/fsck.c
+++ b/builtin/fsck.c
@@ -778,7 +778,7 @@ int cmd_fsck(int argc, const char **argv, const char *prefix)
 	 * default ones from .git/refs. We also consider the index file
 	 * in this case (ie this implies --cache).
 	 */
-	if (!heads) {
+	if (!argc) {
 		get_default_heads();
 		keep_cache_objects = 1;
 	}
diff --git a/t/t1450-fsck.sh b/t/t1450-fsck.sh
index 2f3b05276..96b74dc9a 100755
--- a/t/t1450-fsck.sh
+++ b/t/t1450-fsck.sh
@@ -610,4 +610,15 @@ test_expect_success 'fsck $name notices bogus $name' '
 	test_must_fail git fsck $_z40
 '
 
+test_expect_success 'bogus head does not fallback to all heads' '
+	# set up a case that will cause a reachability complaint
+	echo to-be-deleted >foo &&
+	git add foo &&
+	blob=$(git rev-parse :foo) &&
+	test_when_finished "git rm --cached foo" &&
+	remove_object $blob &&
+	test_must_fail git fsck $_z40 >out 2>&1 &&
+	! grep $blob out
+'
+
 test_done
-- 
2.11.0.642.gd6f8cda6c