[PATCH v2 5/5] format-patch: pick up branch description when no ref is specified

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

We only try to get branch name in "format-patch origin" case or
similar and not "format-patch -22" where HEAD is automatically
added. Without correct branch name, branch description cannot be
added. Make sure we always get branch name.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 builtin/log.c           | 16 +++++++++++++---
 t/t4014-format-patch.sh |  7 +++++++
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/builtin/log.c b/builtin/log.c
index 039bf67..81683f6 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -1027,12 +1027,22 @@ static char *find_branch_name(struct rev_info *rev)
 		else
 			return NULL;
 	}
-	if (positive < 0)
+	if (positive >= 0)
+		ref = rev->cmdline.rev[positive].name;
+	else if (!rev->cmdline.nr && rev->pending.nr == 1 &&
+		 !strcmp(rev->pending.objects[0].name, "HEAD"))
+		/*
+		 * No actual ref from command line, but "HEAD" from
+		 * rev->def was added in setup_revisions()
+		 * e.g. format-patch --cover-letter -12
+		 */
+		ref = "HEAD";
+	else
 		return NULL;
-	ref = rev->cmdline.rev[positive].name;
 	if (dwim_ref(ref, strlen(ref), branch_sha1, &full_ref) &&
 	    !prefixcmp(full_ref, "refs/heads/") &&
-	    !hashcmp(rev->cmdline.rev[positive].item->sha1, branch_sha1))
+	    (positive < 0 ||
+	     !hashcmp(rev->cmdline.rev[positive].item->sha1, branch_sha1)))
 		branch = xstrdup(full_ref + strlen("refs/heads/"));
 	free(full_ref);
 	return branch;
diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
index 903a797..7e52941 100755
--- a/t/t4014-format-patch.sh
+++ b/t/t4014-format-patch.sh
@@ -998,4 +998,11 @@ test_expect_success 'cover letter using branch description (5)' '
 	grep hello actual >/dev/null
 '
 
+test_expect_success 'cover letter using branch description (6)' '
+	git checkout rebuild-1 &&
+	test_config branch.rebuild-1.description hello &&
+	git format-patch --stdout --cover-letter -2 >actual &&
+	grep hello actual >/dev/null
+'
+
 test_done
-- 
1.8.0.rc2.23.g1fb49df