Re* [PATCH v7 00/17] port branch.c to use ref-filter's printing options

Junio C Hamano [off-list ref] writes:

Something like this needs to go before that step.

This time with a log message and an additional test.  The second
paragraph of the proposed log message is written expecting that this
patch will come before your "branch: use ref-filter printing APIs",
which I think is a good place to avoid breakage in the series.

-- >8 --
Subject: [PATCH] for-each-ref: do not segv with %(HEAD) on an unborn branch

The code to flip between "*" and " " prefixes depending on what
branch is checked out used in --format='%(HEAD)' did not consider
that HEAD may resolve to an unborn branch and dereferenced a NULL.

This will become a lot easier to trigger as the codepath will now be
shared with "git branch [--list]".

Signed-off-by: Junio C Hamano <redacted>
---
 ref-filter.c             | 2 +-
 t/t3203-branch-output.sh | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/ref-filter.c b/ref-filter.c
index 944671af5a..c71d7360d2 100644
--- a/ref-filter.c
+++ b/ref-filter.c

@@ -1318,7 +1318,7 @@ static void populate_value(struct ref_array_item *ref)
 
 			head = resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
 						  sha1, NULL);
-			if (!strcmp(ref->refname, head))
+			if (head && !strcmp(ref->refname, head))
 				v->s = "*";
 			else
 				v->s = " ";

diff --git a/t/t3203-branch-output.sh b/t/t3203-branch-output.sh
index d8edaf27e9..1a8dbca8c8 100755
--- a/t/t3203-branch-output.sh
+++ b/t/t3203-branch-output.sh

@@ -37,6 +37,14 @@ test_expect_success 'git branch --list shows local branches' '
 	test_cmp expect actual
 '
 
+test_expect_success 'same, but on an unborn branch' '
+	test_when_finished "git checkout master" &&
+	git checkout --orphan naster &&
+	git branch --list >actual &&
+	sed -e "s/\* /  /" expect >expect-unborn &&
+	test_cmp expect-unborn actual
+'
+
 cat >expect <<'EOF'
   branch-one
   branch-two

-- 
2.11.0-rc1-154-gcd2a643dcd