[RFC PATCH 4/5] format-patch: teach --range-diff to respect -v/--reroll-count

[Eric Sunshine <sunshine@sunshineco.com>]

The --range-diff option introduces the embedded range-diff generically
as "Changes since previous version:", however, we can do better when
--reroll-count is specified by emitting "Changes since v{n}:" instead.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
---
 builtin/log.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/builtin/log.c b/builtin/log.c
index e38cf06050..3089d3a50a 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -1121,7 +1121,11 @@ static void make_cover_letter(struct rev_info *rev, int use_stdout,
 
 	if (diff.len) {
 		FILE *fp = rev->diffopt.file;
-		fputs(_("Changes since previous version:"), fp);
+		if (rev->reroll_count <= 0)
+			fputs(_("Changes since previous version:"), fp);
+		else /* RFC may be v0, so allow -v1 to diff against v0 */
+			fprintf(fp, _("Changes since v%d:"),
+				rev->reroll_count - 1);
 		fputs("\n\n", fp);
 		fputs(diff.buf, fp);
 		fputc('\n', fp);
-- 
2.17.1.1235.ge295dfb56e