[PATCH v2 07/10] sequencer.c: teach append_signoff to avoid adding a duplicate newline

[Brandon Casey <drafnel@gmail.com>]

Teach append_signoff to detect whether a blank line exists at the position
that the signed-off-by line will be added, and avoid adding an additional
one if one already exists.  This is necessary to allow format-patch to add a
s-o-b to a patch with no commit message without adding an extra newline.  A
following patch will make format-patch use this function rather than the
append_signoff implementation inside log-tree.c.

Signed-off-by: Brandon Casey <bcasey@nvidia.com>
---
 sequencer.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index d4a2ece..d51e6f2 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -1114,11 +1114,15 @@ void append_signoff(struct strbuf *msgbuf, int ignore_footer, int no_dup_sob)
 	for (i = msgbuf->len - 1 - ignore_footer; i > 0 && msgbuf->buf[i - 1] != '\n'; i--)
 		; /* do nothing */
 
-	if (i)
-		has_footer = has_conforming_footer(msgbuf, &sob, ignore_footer);
-
-	if (!has_footer)
-		strbuf_splice(msgbuf, msgbuf->len - ignore_footer, 0, "\n", 1);
+	if (msgbuf->buf[i] != '\n') {
+		if (i)
+			has_footer = has_conforming_footer(msgbuf, &sob,
+					ignore_footer);
+
+		if (!has_footer)
+			strbuf_splice(msgbuf, msgbuf->len - ignore_footer, 0,
+					"\n", 1);
+	}
 
 	if (has_footer != 3 && (!no_dup_sob || has_footer != 2))
 		strbuf_splice(msgbuf, msgbuf->len - ignore_footer, 0,
-- 
1.8.1.1.252.gdb33759