Fix format.headers not ending with a newline

Now each value of format.headers will always be treated as a single
valid header, and newlines will be inserted between them as needed.

Signed-off-by: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-log.c

@@ -425,10 +425,14 @@ static int git_format_config(const char *var, const char *value)
 		if (!value)
 			die("format.headers without value");
 		len = strlen(value);
-		extra_headers_size += len + 1;
+		while (value[len - 1] == '\n')
+			len--;
+		extra_headers_size += len + 2;
 		extra_headers = xrealloc(extra_headers, extra_headers_size);
-		extra_headers[extra_headers_size - len - 1] = 0;
+		extra_headers[extra_headers_size - len - 2] = 0;
 		strcat(extra_headers, value);
+		extra_headers[extra_headers_size - 2] = '\n';
+		extra_headers[extra_headers_size - 1] = 0;
 		return 0;
 	}
 	if (!strcmp(var, "format.suffix")) {

t/t4014-format-patch.sh

@@ -101,7 +101,7 @@ test_expect_success 'extra headers' '
 	
 '
 
-test_expect_failure 'extra headers without newlines' '
+test_expect_success 'extra headers without newlines' '
 
 	git config --replace-all format.headers "To: R. E. Cipient <rcipient@example.com>" &&
 	git config --add format.headers "Cc: S. E. Cipient <scipient@example.com>" &&