format-patch: show 0/1 and 1/1 for singleton patch with cover letter

Change the default behavior of git-format-patch to generate numbered
sequence of 0/1 and 1/1 when generating both a cover-letter and a single
patch. This standardizes the cover letter to have 0/N which helps
distinguish the cover letter from the patch itself. Since the behavior
is easily changed via configuration as well as the use of -n and -N this
should be acceptable default behavior.

Add tests for the new default behavior.

Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/log.c

@@ -1650,16 +1650,16 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 		/* nothing to do */
 		return 0;
 	total = nr;
-	if (!keep_subject && auto_number && total > 1)
-		numbered = 1;
-	if (numbered)
-		rev.total = total + start_number - 1;
 	if (cover_letter == -1) {
 		if (config_cover_letter == COVER_AUTO)
 			cover_letter = (total > 1);
 		else
 			cover_letter = (config_cover_letter == COVER_ON);
 	}
+	if (!keep_subject && auto_number && (total > 1 || cover_letter))
+		numbered = 1;
+	if (numbered)
+		rev.total = total + start_number - 1;
 
 	if (!signature) {
 		; /* --no-signature inhibits all signatures */

t/t4021-format-patch-numbered.sh

@@ -36,6 +36,11 @@ test_no_numbered() {
 	test_num_no_numbered $1 2
 }
 
+test_single_cover_letter_numbered() {
+	grep "^Subject: \[PATCH 0/1\]" $1 &&
+	grep "^Subject: \[PATCH 1/1\]" $1
+}
+
 test_single_numbered() {
 	grep "^Subject: \[PATCH 1/1\]" $1
 }
@@ -121,4 +126,16 @@ test_expect_success '--start-number && --numbered' '
 	grep "^Subject: \[PATCH 3/3\]" patch8
 '
 
+test_expect_success 'single patch with cover-letter defaults to numbers' '
+	git format-patch --cover-letter --stdout HEAD~1 >patch9.single &&
+	test_single_cover_letter_numbered patch9.single
+'
+
+test_expect_success 'Use --no-numbered and --cover-letter single patch' '
+	git format-patch --no-numbered --stdout --cover-letter HEAD~1 >patch10 &&
+	test_no_numbered patch10
+'
+
+
+
 test_done